Summary: This paper is concerned with three waves of H7N9 avian influenza epidemic which occurred in China from 2013 to 2015. Based on the real data of the infectious cases issued by the World Health Organization (WHO), logistic growth model is used and the fitting curves agree with the original data. By considering the impact of the temperature in the latent period and the best-fit temperature, the classical Logistic growth model is improved and computations show that the best-fit temperatures for three waves are 15.0132\celsius, 8.517\celsius and 6.624\celsius, which implies that the improved model is better for describing the avian influenza and the best-fit temperatures are different for different periods.