Low platelets means that the number of platelets in the peripheral blood is lower than the normal range. Low platelets are clinically seen in a variety of diseases, most of which are hematologic diseases, the common ones are: a. Immune thrombocytopenic purpura, which is the most common clinical disease causing thrombocytopenia and is also an autoimmune disease. Due to the disturbance of immune balance, antibodies against self platelets are produced, which leads to excessive destruction of platelets in peripheral blood, resulting in the symptoms of thrombocytopenia and bleeding. Second, aplastic anemia, a bone marrow hematopoietic failure disease, can also appear thrombocytopenia. Third, certain malignant diseases of the hematological system, including leukemia, myelodysplastic syndrome, multiple myeloma, and advanced stages of lymphoma, which destroy the body’s hematopoietic stem cells and prevent megakaryocytes from proliferating and dividing normally, can also present with thrombocytopenia.