The present invention discloses a method for remolding bone marrow microenvironment in a subject having an impaired bone marrow microenvironment, which comprises implanting a composition comprising isolated mesenchymal stromal cells (MSCs) into the bone marrow cavity of the subject. The method of the present invention successfully remolds the bone marrow microenvironment, recovers the normal hematopoiesis of bone marrow, inhibits/delays the pathological process of leukemia and significantly prolongs the survival period. In addition, the method according to the present invention can be used for the treatment of hematologic tumors such as leukemia and aplastic anemia (AA), which is safe and effective but has no side effects.