Bladder tumor is one of the most common tumors in urology and the most common tumor of the urinary system. According to the pathological classification, bladder tumors can be divided into two categories: epithelial and non-epithelial; the incidence of the former accounts for about 98%, far exceeding that of the latter, and is the most clinically significant tumor in urology. [Pathological classification] ①Papillary tumor: benign, can be transformed into malignant tumor. (2) Involutional papilloma: most of them are benign, a few are associated with malignant transformation. ③Papillary metastatic epithelial carcinoma: divided into highly differentiated, moderately differentiated and poorly differentiated. ④Non-papillary metaplastic epithelial carcinoma: it is invasive malignant tumor. ⑤ Carcinoma in situ: it is an early lesion with potential malignancy. ⑥Adenocarcinoma: less common, accounting for 1%-1.8% of epithelial cell tumors. (7) Squamous carcinoma: less common, accounting for 1.6-0.7% of epithelial cell carcinoma. (8) Undifferentiated carcinoma: high malignancy, rapid infiltration and metastasis. [Diagnosis] ① Clinical manifestations: Most of them are above 40 years old, often presenting painless hematuria, which may be accompanied by bladder irritation symptoms such as urinary frequency, urinary urgency and pain, as well as urinary tract infection, anemia and lumbago. Advanced patients have lower limb swelling, sacroiliac and lumbar compression pain, and metastatic lesions in the liver, lung and bone. ②Urine cytology examination: tumor cells can be found and the general morphology of tumor cells can be understood, the positive rate is 30%-70%. ③Cystoscopy: it can detect the existence of tumor and grasp the tumor location, size, number and relationship with surrounding; tumor tissue biopsy can confirm the nature of tumor. ④X-ray: (i) retrograde cystography: it can find out the filling defect in bladder, and whether there are changes of bladder wall such as stiffness and deformation; (ii) excretory pyelogram: to understand whether there are tumors or other abnormalities in kidney and ureter; (iii) bladder arteriogram: to see the distribution of bladder tumor vessels; (iv) CT: to understand whether there is infiltration of bladder tumor, the accuracy rate is 40%-81%, and it can see the thickening and deformation of bladder wall and enlarged lymph nodes. (iii) CT: the accuracy rate is 40%-81% for understanding whether the bladder tumor is infiltrated or not. (⑤) Ultrasound: bladder tumors with diameter above 1.0 cm can be detected; ultrasound examination via urethra or rectum is important to understand the depth of tumor infiltration and clinical stage. ⑥Magnetic resonance imaging (MRI): it can understand the depth of bladder tumor infiltration and whether there is metastasis and enlargement of lymph, and its accuracy rate is 64%-95%.