Objective To explore the prognostic value of red cell volume distribution width (RDW) for hematological malignancies. Methods PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang, Chongqing VIP, and SinoMed were searched for related literatures on myelodysplastic syndrome, leukemia and other hematological malignancies and pretreatment RDW from the establishment of databases to April 5, 2022. The main statistical indicators were Hazard ratio (HR) and its 95% confidence interval (CI). Stata 12.0 SE software was used for analysis, and Q test was used to evaluate literature heterogeneity. Subgroup pooled analysis was used to evaluate the prognostic value of RDW. Results A total of 7 articles were included, with a total of 804 patients. A fixed-effect model was selected for meta-analysis, and the results showed that patients with elevated pretreatment RDW had worse overall survival [HR=2.91, 95%CI (2.01, 4.22), I2=0%, P=0.714]. The results of subgroup analysis for different types of diseases showed that in myelodysplastic syndrome group [HR=2.61, 95%CI (1.28, 5.31), I2=22.0%, P=0.258)], chronic myeloid leukemia group [HR= 3.24, 95%CI (1.91, 5.51), I2=0%, P=0.546], and adult T-cell leukemia/lymphoma group [HR=2.64, 95%CI (1.22, 5.70)], the overall survival rate of patients with elevated pretreatment RDW were worse. Sensitivity analysis showed that the study was stable and there was no heterogeneity in the overall study result.Conclusion Elevated pretreatment RDW is associated with overall survival and can be used as an indicator for evaluating the prognosis of hematological malignancies, but large sample studies are still needed to determine the best predictive cutoff for various diseases.