Low leukocytes after chemotherapy for gastric cancer is a relatively common clinical myelosuppression. Myelosuppression can be classified into different levels according to low leukocytes, neutropenia and platelet depression, and the treatment means are different for different levels. The degree of myelosuppression varies according to the chemotherapy drugs commonly used in gastric cancer. Common carboplatin may cause higher degree of myelosuppression than cisplatin, chemotherapeutic agents such as VP16 and irinotecan can cause very severe myelosuppression, and common docetaxel has higher myelosuppressive side effects than paclitaxel. To prevent myelosuppression in patients, it is important to enhance nutrition and pay attention to nutritional intake before, during and after treatment. Patients should prevent colds and flu, and patients with previous high-risk factors can apply colony-stimulating factor prophylactically to prevent very severe myelosuppression. If a patient develops more severe myelosuppression, not only subcutaneous injection of granulocyte colony-stimulating factor but also prophylactic application of antibiotics should be performed.