Abstract: The excellent self-imcomapatible line“S-89”was bred from Chinese cabbage cultivar“Xian Dabaotuo”by means of selfing for generations, the excellent self-imcomaptible line“S-75”was bred from cultivar“Mudanjiang No1”by mean of selfing for generations.The combining abili-ty and index of compatibility of these lines were tested and analysed strictly.Finally by crossing“S-89”and“S-75”Medium Maturing No4”was bred and named.This hybrid haxhigh resistance to disease,high productivity and excellent adaptability,better quality and other commercial charac-terlstics.It is with shorter growing perlod.Now it becomes the most medium-maturing and late-maturing Chinese Cabbage cultivated in Fuzhou area. It was spreaded inxeverl areas in south Chi-na.In the National Regional Trial of Medium-rnaturing and Late-maturing Chinese Cabbage held in Fujian in 1994,it was determined to be the best hybrid with high productivity,high resistance to disease and with good quality.It has been approved and qualified by the provincial and Municipal Committee of Cultivar examination and Approval.It was awarded the firstclass scientific and tech- nical progress prize from Fuzhou Governrnent in 1995.