Abstract:The analysis of karyotype of an endangered plant endemic to China, Paeonia delavayi var. lutea is presented. The karyotype formula is K(2n)=10=6m(2SAT)+2sm+2st(SAT). The micro-satellites are on the short arms of 3rd and 5th pairs of chomosomes. According to the Stebbins‘classification of karyotype asymmetry, the karyotype belongs to"2A" type.Based on the comparison of propotional length of chromosomes of P. delavayi var. lutea with that of other plants in section Moutan, we discussed the interspecific relationship and presented cytological evidence of subsection division in section Moutan.