This study was aimed to investigate the expression level of Wilms' tumor 1( WT1) gene in hematologic neoplasm (leukemia, multiple myeloma and lymphoma) patients and its clinical significance. Real-time quantitative polymerase chain reaction (RQ-PCR) was used to detect the copy number of WT1 gene and reference gene (ALB) in bone marrow cells of 228 patients with hematologic neoplasm in our hospital. The gene expression level was determined by using the ratio of the copy number of WT1 gene and reference gene. The results showed that the WT1 expression level between male and female patients was not statistically significantly different (P > 0.05). All the patients were divided into 3 groups: the group aged under 19, the group aged between 19-50, and the group aged over 50; the WT1 expression level among the three groups were not statistically significantly different (P > 0.05) . The above-mentioned patients were redivided into the groups aged under 45 and over 45, the difference between them was not statistically significant (P > 0.05). The difference of WT1 expression level between newly diagnosed patients and treated patients with hematologic neoplasm was statistically significant (P < 0.01), but no statistically significant difference of WT1 expression was found (P > 0.05) at each stage within 3 years after treatment, however, among them the difference between newly diagnosed leukemia patients and treated leukemia patients was very statistically significant (P < 0.01), while the difference between newly diagnosed and treated non-leukemia patients was not statistically significant (P > 0.05). The expression difference of WT1 between leukemia and non-leukemia patients was very statistically significant (P < 0.01), the difference between the newly diagnosed leukemia and non-leukemia patients also was very statistically significant (P < 0.01). The difference of WT1 expression between treated leukemia and non-leukemia patients was not statistically significant (P > 0.05). It is concluded that the WT1 expression level in leukemia patients can be a reliable marker to evaluate the prognosis of newly diagnosed leukemia and the curative effect for minimal residual disease. No WT1 expression difference has been found before and after treatment among the patients with non-leukemia, such as multiple myeloma and lymphoma, therefore, which should be furtherly explored.