In order to improve the practicability of maize DUS test guideline in China,while doing the practical testing workt,he variation and distribution type of 9 quantitative characteristics including the tassel length of main axis above lowest side brancht,assel length of main axis above upper side brancht,assel length of side branches,plant height and so on were studied with the help of the computer and probability theory.Meantime,the probability distribution was discussed and recommended.This will supply certain theoretical basis for different ecotype in doing DUS testing of new maize varieties.