Bone marrow aspiration is a diagnostic technique by extracting bone marrow for cytological, bacteriological and parasitological examinations. The indications mainly include anemia of various unexplained causes, thrombocytopenia, leukopenia or holocytopenia, clinical suspicion of leukemia and observation of efficacy during leukemia treatment, fever of unknown cause requiring bone marrow examination or culture, bone marrow cavity injection for leukemia, bone marrow stem cell culture or bone marrow transplantation, bone marrow metastasis of various malignant tumors, bone marrow infiltration of lymphoma, etc. Contraindications are thrombocytopenia or abnormal coagulation function, and attention should be paid to the absence of bleeding when performing puncture, and absolute contraindication is hemophilia.