Abstract: The DUS testing of plant variety is a necessary procedure and important means for variety authorization, registration and identification, and law enforcement of rights protection. Based on field tests conducted on 36 standard varieties in corn DUS test guidelines in 2018—2019, the difference between the traits of performance of standard varieties in Guizhou and the code in maize test guide was analyzed by coincidence coefficient, and the expression accuracy and morphological diversity of maize standard varieties in Guizhou were also evaluated. The results showed that 30 of the 36 standard varieties had coincidence coefficients greater than 0.95, accounting for 83.3%, while 30 of the 39 tested traits had coincidence coefficients greater than 0.95, accounting for 76.9%. And, the average coincidence coefficients were quality traits（1） ＞ pseudoquality traits（0.982）＞ quantitative traits（0.967）. The 199 allelic variations of 39 traits were detected in 36 standard varieties with a variable range of 1 to 9, with an average of 5.103. Additionally, the effective alleles ranged from 1 to 6.694, with an average of 3.282, and Shannon-weaver diversity index ranged from 0 to 2.008, with an average of 1.234. The morphological similarity coefficients of the 36 standard varieties ranged from 0.64 to 0.84, and the 36 standard varieties could be divided into 31 groups while the similarity coefficients were 0.81, so the number of standard varieties could be reduced to 31.