In order to analyze the performance of gas turbine inlet anti-icing system and reduce the risk of filter burn, the effects of different jet hole diameter, the number of holes and bleed air flow rate on the mixing effect of a gas turbine anti-icing system and mainstream were discussed by using three-dimensional numerical simulation method. The mixing phenomenon of bleed air ejected from jet holes with mainstream and the whole process of its downstream transportation are presented. Simulation result shows that blowing ratio (Br) is the key parameter affecting the mixing of hat gas and mainstream. Reducing jet hole diameter and increasing bleed air flow rate will increase Br both, and the hot bleed air and the mainstream cold air are mixed more evenly. When the jet hole diameter and the flow rate of bleed air remain unchanged, increasing the number of jet holes will not play a positive role in mixing.