Abstract: This paper deals with the karyotypes in six species of Crotalaria Linn. in Yunnan The result shows that C. albida is of K2n=2x=16=14m+2sm(SAT), C. linifolia K2n=2x=16=14m+2sm(SAT), C. bracteata K2n=2x=16=14m+2sm(SAT), C. pallida K2n=2x=16=14m+2st(SAT), C. medicaginea K2n=2x=16=12m+2sm(SAT)+2st(SAT), and C. ferruginea var. ferruginea K2n=6x=48=42m+4sm(SAT)+2st(SAT)*. All of the species are diploid(2n=2x=16), but C. ferruginea var. ferruginea is hexaploid(2n=6x=48). The chromosomal evolution of these species is discussed Chromosome number and karyotype of C. bracteata and chromosome number of C. yunnanensis are here reported for the first time.The karyotype asymmetry demonstrates that all six species belong to 2A, which indicates that the karyotypes in these species are similar, but variation in "Number and Position of SAT.; SAT Length/Short Arm Length; The Longest Chromosome/The Shortest Chromosome; Proportion of Chromosomes with Arm Ratio>2: 1(%)" among them is clear. These changes in karyotypes suggest the chromosomal evolution in six species are: C. bracteata→C. pallida→C, linifolia→C. albida→C. ferruginea var, ferruginea→C. medicaginea, which agrees with Polhill’s Taxonomical System of Crotalaria(1982).Each species is of one or two pairs of satellites which are located on short arms and the satellites are longer than the short arms. The asymmetry of the karyotypes goes high with increase of the numbers of satellites. The number of satellites also increases with polyploidy of the complement in C. ferruginea var. ferruginea. Usually, the size and position of satellites are unstableC. ferruginea includes two varieties. C. ferruginea var. ferruginea is a hexaploid, distributed in Asia from tropics to subtropics and even to warm temperate; and var. pilosissima is a diploid, distributed in India only, which suggests that the latter is more primitive.