Abstract: This study intended to improve the quality of the existing cytoplasmic male sterile (CMS) line in Brassica napus with high combining ability. The CMS line Nan A2 was used as female parent, crossed and continuous backcrossed with the conventional double low strain 92-2. Meanwhile, quality directional selection in progenies and combining ability analysis on advanced generations were adopted to accelerate the selective breeding speed of male sterile line. The results of the study were as follows. Nan A6, a new cytoplasmic male sterile line with low erucic acid and low glucosinolate, was successfully bred. It passed the examination organized by Sichuan Provincial Crop Variety Approval Committee in March 2002. It had the characteristics of stable sterility, good quality, high general combining ability, excellent agronomic traits, high outcrossing rate, strong resistance (tolerance) of lodging and diseases, wide adaptability. And Nan A6, crossed with six restorer lines, had made out of two high-yield combinations and four high-quality combinations authorized by the Provincial or National Crop Variety Approval Committee subsequently. The study indicated that Nan A6 had become one of main sterile lines in male sterile heterosis utilization in Sichuan Province, and had broad application prospects.