Morphology of cytoplasmic-genic male sterility line RC₇ and its maintainer line of Chinese cabbage were microscopically studied to make clear RC₇ abortive period and mode,analysis of gene expression in bud by using cDNA-AFLP technology,which will provide a scientific basis for Chinese cabbage on molecular mechanism of CMS.（1）The microspore mother cells perform the simultaneous type of meiosis.The microspores are arranged in a tetrahedral shape in the tetrad,and the tapetum of the maintainer line belongs to glandular type.The male sterile RC₇ shows larger vacuoles in the tapetum cell,which is abortion signs.In uninucleate stage,tapetal disintegration,middle cell disappeared and microspore nucleus began to collapse,which belongs to uninucleate abortion type.（2）The gene expression in flower buds of CMS line and its maintainer line was compared by means of cDNA-AFLP,a total of 23 differential transcript-derived fragments (TDFs) were identified and sequenced.8 TDFs were expressed specifically in CMS line,whereas 10 could be detected only in the maintainer line,moreover 5 TDFs were expressed both two lines.（3）The result of GenBank BLAST showed that H1 TDFs coming from CMS line shared higher identity with photoassimilate-responsive protein of Arabidopsis thaliana,H29 TDFs shared higher identity with calcineurin-like phosphoesterase family of A.thaliana.10 TDFs from maintainer line were highly identical to known sequences.These genes might be related to glucose metabolism,protein synthesis and transport,ethylene-inducible gene,electron transport and energy pathway,unknown or putative protein and so on.The results showed that the reason for the abortion was possibly that the tapetum cells were subjected to hypertrophy via vacuolation so that the microspores were extruded and broken into pieces,that makes the bicellular pollen grains could not form.Ehylene induced genes (H29) specifically expressed in the maintainer line,silenced in the sterile lines,which indicated that lack of sterile lines of ethylene related genes.