Abstract: [Objective] This study aims to make preliminary understanding of the relationship between relative growing degree days(GDD)and the relative plant height of different cotton varieties in order to provide theoretical reference for relative effective temperature monitoring of cotton plant height change by using the normalization method and clustering analysis through varieties tests.[Method]In this study,the experiment used 29 varieties which are widely planted in Xinjiang.The height of cotton plant was measured by fixed points and fixed plants for every 7 days starting from the three-leaf stage;and the meteorological data of the same year was obtained from Shihezi Meteorological Bureau.[Result]The result showed that the relative height of the cotton plant changed consistently with relative GDD in spite of different varieties.Here we established three categories of simulation model about plant height based on relative GDD: Y=a/(1+exp(b-cX))1d.Among these,the class I(from 3-leaf stage(relative plant height value was less than 0.14)to 11-leaf stage(relative plant height value was less than 0.7),the growth rate of plant height was slow): Y=0.997/(1+exp(26.08-33.62X))1/8.66(r=0.997,6);The class II(from 3-leaf stage(relative plant height value between 0.14-0.18)to 11-leaf stage(relative plant height value between 0.7 to 0.8),the growth rate of plant height was fast): Y=0.997/(1+exp(26.09-28.65X))1/8.41(r=0.996,7).The class III(from 3-leaf stage(relative plant height value was greater than 0.18)to 11-leaf stage(relative plant height was greater than 0.8),the growth rate of plant height was superbly fast): Y=1.02/(1+exp(8.55-12.68X))1/3.25(r=0.997,3).We tested the mode and the results showed that the value of RMSE was 1.699,8 cm,indicating that the error between simulated and observed values was relatively small.[Conclusion]Therefore,Richards function can effectively predict the changes of plant height in cotton.But the comprehensive factors such as light,temperature driven cotton plant height simulation model still need further study.