Abstract: An AFLP and RAPD genetic map with 352 markers was employed in mapping and analysis ql'gcontrolling heat tolerance in Brassica camistris L． ssp．pekinensis，using composite interval mapping method．Heat damage index in seedlings WaS used as phenotypic value to detect quantitative trait loci．Five ql'g weI'e pped in three linkage groups．Three loci including ht-1， lu-3 and lu-5 showed positive additive efect， while ht-2 and _4 showed negative additive efect． Out of the five rL， pbenotypic variation explained by ht-2 WaS
the biggest one。and then ht-5．The distance from the nearest flanking markers to ql'g ranged from 0．1 cM to 2．4 cM．These markers provided useful information for molecular marker assistant selection of heat tolerance in breeding programmes of Chinese cabbage．

Key words: Brassica cam~stris L．ssp．pekinensis, Heat tolerance, Quantitative trait loci(ql'g)