Abstract: 【 Objective 】 In order to further clarify the density effect of (LAI) characteristic parameters of leaf area coefficient of cotton populations with different densities, the effects of different densities on the dynamic characteristic parameters of LAI were simulated and analyzed by using the relative LAI dynamic universal model equation y = (a+bx) / (1+cx+dx²) of high yield populations. 【 Method 】 Different genotypic hybrid cotton varieties Zhaofeng No.1 (land and land hybrid F₁ generation) and Xinluzhong 31 (sea and land hybrid F₁ generation) were selected as testing varieties and sown on April 22. Planting arrangement of drip irrigation under plastic film (10+66+10+66+10+66)cm, 1 tube 3 mode. Eight planting density treatments (according to the number of harvest plants) were set up, which were 7.2 ×10⁴ plants/ hm², 10.22 ×10⁴ plants/ hm², 13.14 ×10⁴ plants/ hm², 16.58 ×10⁴ plants/ hm², 19.62 ×10⁴ plants/ hm², 22.26 ×10⁴ plants/ hm², 24.70 ×10⁴ plants/ hm², and 28.80 ×10⁴ plants/ hm² (denoted as T1, T2, T 3, T 4, T 5, T 6, T 7, T 8, respectively), arranged in a random area group and repeated three times, and 3 films of 18 lines were planted in each area, with an area of 74.8 m². 【 Result 】The maximum LAI of cotton population increased approximately linearly with the increase of density in the range of 7.2×10⁴-28.8×10⁴ plants/hm² , showing an approximate linear increasing trend, while the time when the maximum LAI appeared was earlier with the increase of density; After the relative processing of LAI data, the LAI difference of different density populations was more obvious after the maximum LAI, and the LAI attenuation of high density population was faster than that of low density population. The average LAI of the whole growth period increased linearly with the increase of density. The density had different effects on the parameters of the simulation equation. The change rate of LAI in the whole growth period showed the trend of "N" shape, and corresponded to the change of population LAI and the growth period, the increase and attenuation rate of LAI in high density population was higher than that in low density population.【 Conclusion 】 Density plays an important role in regulating the dynamics of LAI in cotton whole growth population, especially in regulating groups LAI. The maximum LAI and its arrival time, average LAI and other important characteristic parameters are sensitive to density response, which can be used as the reference index of cotton population density regulation.