〔Abstract〕 Objective To compare the efficacy and safety of total body irradiation(TBI) and total bone marrow and lymphoid irradiation(TMLI) combined with chemotherapy for unrelated cord blood transplantation(UCBT) in the treatment of hematological malignancies. Methods Retrospective analysis was performed on 45 patients with hematological malignancies who received UCBT in the affiliated Provincial Hospital of Anhui Medical University. They were divided into TBI group(31 cases) and TMLI group(14 cases) according to different conditioning regimens, in which TBI was performed by electron linear accelerator and TMLI was performed by tomotherapy. The hematopoietic reconstruction, the dose of organs at risk(OAR), the acute and chronic toxic and side effects, and the safety and effectiveness of TMLI dose climbing in the two groups were analyzed and compared. Results The median time of neutrophil engraftment in the TBI group and the TMLI group was 19.50(16-29) days and 16.50(12-38) days respectively(P=0.005), and the cumulative neutrophil engraftment rate by day 42 was 90.32%(95%CI: 88.17%-92.47%) and 100%(95%CI: 97.14%-102.86%)(P=0.025), respectively. The gastrointestinal reaction in the TMLI group was less and the overall treatment time was shorter. Conclusion TMLI provides a new option for patients with refractory leukemia, who cannot tolerate high-dose chemotherapy or cannot adhere to complete TBI. When TMLI dose climbs to 15 Gy, adverse reactions can be tolerated.