Abstract: The male sterile line of Chinese cabbage with rape cytoplasm, which sterility has been changeover dealt with low temperature（AT line）, the male sterile line with no treatment （A line）and it’s maintainer (B line ) were used in the experiment. The POD, ATP, AMY，EST isozymes were analyzed with the roots and leaves of seedling stage with six leaves, large buds, middle buds and small buds of flower stage by using vertical slab polyacrylamide gel electrophoresis. The results are shown as follow: POD, ATP, AMY have no notable relations with sterility. EST have no differences in seedling stage between A line and B line, but there are notable differences in small buds (EST’s activity of maintainer is stronger than that of sterile line. There are the bands of α-Est with Rf 0.62,0.68,0.72,0.75,0.83 in maintainer more than that of sterile line and the bands of β-Est with Rf 0.68,0.72,0.75,0.83 of maintainer more than that of sterile line).The band of α-Est with Rf 0.83 was disappeared with the changeover of sterility by the treatment of low temperature, which may be related with the changeover of sterility. Based on the experiment the mechanisms of cytoplasm male sterility are also discussed in this paper.