Abstract: N,N,N’,N’-tetraoctyl-3-oxapentanediamide（TODGA） is the most commonly used diglycolamide extractant. N,N,N’,N’-tetraoctyl-2-methyl-3-oxapentanediamide（Me-TODGA）is a derivative of TODGA and which is a promising substitute of TODGA for high level liquid waste separation process. In this paper, the extraction of trivalent actinides, lanthanides and fission elements such as Sr（Ⅱ）, Zr（Ⅳ）, Pd（Ⅱ） by Me-TODGA was evaluated to compare with that of TODGA. The influence of radiolysis on extraction properties of the two diglycolamide extractants was also studied. The results show that third phase is formed with Me-TODGA and TODGA extraction at high concentration metal ion. However, it is avoided by addition of 0.50 mol/L TBP. The extraction of actinides, lanthanides and fission products with Me-TOGDA/TBP system is weaker than the TOGDA/TBP system, which is beneficial to stripping of trivalent actinides/lanthanides and scrubbing of fission elements. The distribution ratio（logarithm value） of Eu（Ⅲ） and Sr（Ⅱ） with Me-TOGDA and TOGDA decreases linearly with increasing irradiation dosage. Me-TODGA is not stable than TODGA, and the stability is improved by addition of TBP. Comparatively, Me-TODGA is not stable than TODGA