Breast-conserving treatment has become one of the treatment options for early-stage breast cancer. The goal is to strive for optimal local control while ensuring good aesthetic results and quality of life. However, 20% to 30% of breast-conserving patients rate their postoperative appearance as fair or poor. Especially for some patients with large lesions or small breasts, it is difficult to achieve satisfactory postoperative aesthetic results with breast-conserving surgery. In such cases, breast defects need to be repaired. The methods used to repair breast defects include: fat grafting, transfer of local flaps, breast tissue remodeling, implantation of absorbable synthetic fiber patches or cotton fabric, and transfer of distant flaps. The use of fat grafting for the repair of breast defects is controversial because of its potential to interfere with the diagnosis of breast cancer. Implantation of absorbable synthetic patches or cotton fabric may cause varying degrees of foreign body reaction. Therefore, it is generally accepted that local tissue (including transfer of local flaps and breast tissue remodeling) is preferable for the repair of breast defects after breast-conserving treatment. If the breast defect still cannot be satisfactorily repaired using local tissues, then transfer of distant tissues for advanced repair can be considered. The procedure has the following characteristics: 1. Easy and time-saving operation: the operation takes only 2~3 hours. 2.Less postoperative complications: all the transferred flaps are alive, and there are no serious postoperative complications such as flap necrosis, infection and hematoma. 3.Good postoperative effect: Since most of the natural structure of the breast is preserved, patients are more satisfied with the shape of the reconstructed breast. 4.Does not affect future fertility: long-term postoperative follow-up data showed that all patients did not have tumor recurrence. The use of breast reconstruction with the latissimus dorsi muscle flap immediately after breast-conserving surgery has expanded the indications for breast-conserving surgery. Previously, breast-conserving surgery was thought to be indicated for patients with early-stage breast cancer with lesions located in the peripheral area of the breast. For patients with lesions located in the central area of the breast or large tumors in small breasts, breast-conserving surgery is not an appropriate option because of the unsatisfactory cosmetic results after lesion removal and repair. We believe that good postoperative results can be achieved through breast reconstruction with the latissimus dorsi muscle flap immediately after breast-conserving surgery. Therefore, tumors in the central region of the breast and large tumors in small breasts should no longer be contraindicated for breast-conserving surgery. However, when performing this surgery, the contraindications to the surgery should be strictly controlled. Cases in which breast-conserving surgery is contraindicated include: 1) multiple primary cancer foci, especially in different quadrants; 2) mammograms showing extensive sandy calcifications; 3) pathological examinations showing extensive intraductal cancer lesions. In this view, we believe that although breast reconstruction based on latissimus dorsi muscle flap can expand the resection area of breast-conserving surgery, it is still difficult to ensure negative margins, and the risk of recurrence of breast tumor on the affected side occurring in positive margins is two to three times higher than that of those with negative margins. Therefore, breast-conserving surgery is still not an option for these patients, and it is important to perform thorough physical examination and imaging before surgery to determine the extent of the lesion to decide whether to perform breast-conserving treatment. Mammography is currently the standard screening test for tumors, but the extent of the lesion is often underestimated unless further examination or further testing with other imaging techniques, such as image magnification, is important to observe the extent of suspicious or malignant calcifications. In addition, ultrasound and/or magnetic resonance imaging can complement mammography and physical examination to identify other lesions. In conclusion, there are many different ways to repair breast defects after breast-conserving surgery. Breast defect repair using the latissimus dorsi muscle flap is an alternative method of breast defect repair because of its ease of surgical operation, low postoperative complications, and good reconstructed breast shape.