Hardness in the left abdomen may be caused by fecal hoarding, colon tumor, abdominal tumor, female ovary and fallopian tube tumor. 1. Fecal matter accumulation: some patients with serious indigestion or long-term constipation may have dried fecal matter accumulation in the descending colon and sigmoid colon, and hard fecal matter will be felt when touching the left abdomen. 2. Colon tumor: when there is a tumor in the descending colon and sigmoid colon on the left side of the abdomen, there is a possibility to feel the mass in the left abdomen. In addition, patients usually have pain and discomfort in the left lower abdomen, increased frequency of stools, thinning of stools, pus and blood stools and other symptoms. 3. Abdominal tumors: when there are tumors in the left abdominal cavity, patients may also feel hard lumps, such as mesenchymal tumors, liposarcoma, fibroma, smooth muscle tumors and so on. 4. Female ovarian and fallopian tube tumors: female patients with left ovarian or fallopian tube tumors may also feel hard lumps when the tumors are large. In addition, lesions on the left side of the abdominal wall may also lead to hard lumps that can be felt in the left abdomen. It is recommended that the patient should consult the doctor in time. Improve the examination, clear diagnosis and follow the doctor’s instructions for appropriate treatment.