In order to establish the relationship between the electricity indexes and air temperature, the influence of air temperature on electricity indexes is analyzed and the nonlinear statistic model is established by using the data of daily demand for electricity, daily maximum load, daily minimum load and the corresponding air temperature data. Compared with the linear model, the nonlinear model can better show the relationship between the electricity indexes and the air temperature. The daily maximum load, the daily demand for electricity and the daily minimum load are most in sensitive to the critical average air temperatures 15～16℃,14～15℃ and 13～14℃ respectively. When the air temperature is higher and lower than the critical temperature, the electricity indexes nonlinearly increase, and the larger the deviation to the critical temperature, the quicker the increase in the electrical load.