Abstract: 【Objective】 To establish the leaf area index estimation model of different varieties of drip irrigation by using the dynamic variation rule of red-edge parameters. 【Method】Taking Xinluzao No.50, Xinluzao No.58 and Lumianyan No. 24 (hybrid cotton) as experimental materials, the dynamic changes of LAI and red edge position were analyzed, and the estimation model of leaf red edge parameter -LAI of drip irrigation cotton was constructed.【Result】The fastest growing period of LAI appeared between 40 and 70 days, but the LAI growth rates of different varieties of drip-irrigation cotton showed obvious differences, which were as follows: Lumianyan No.24 > Xinluzao No.50 > Xinluzao No.58. In this experiment, different varieties of cotton showed blue shift during the occurrence of pests and diseases, and red shift under normal growth of cotton. In this experiment, the red edge parameters were significantly correlated with LAI. Among the three estimation models, Lumianyan No.24 had the highest accuracy (R² = 0.816,8, RMSE = 0.77).【Conclusion】The LAI can be effectively estimated by the established estimation models. The experimental results can provide theoretical basis for promoting the development of precision agriculture in Xinjiang.