Abstract: With phenotypic variation of 20 characters and SSR molecular markers the genetic diversity of 30 maize landraces,including 15 from Yunnan and 15 from Guizhou,was analyzed.Based on the results of t-test and variation coefficient analysis,a high of genetic diversity was found among landraces from both Yunnan and Guizhou.For the 15 landraces from Yunnan,a total of 265 polymorphic alleles were detected and the average number of alleles was 6.3.For the 15 landraces from Guizhou,241 polymorphic alleles were found and the average number of alleles was 5.7.In addition,the genetic diversity was greater in Yunnan than in Guizhou.For genetic variation of SSR loci,the former was higher than latter.The results based on the genetic structure showed that there was an obvious genetic differentiation from Hardy-Weinberg expectation in the landraces from both in Yunnan and Guizhou,and a considerable genetic variation was revealed within rather than among landraces.