How to design an efficient one-way Hash function is always the hot point in mode rn cryptography researches. In this paper, a Hash function construction method b ased on extended chaotic maps switch is proposed. The extended chaotic model is first built to generate various kinds of chaotic signals at different parts of t he original signals according to the switching schemes, and then chaotic paramet ers of one-way Hash function is modulated by the linear-transformed signals. The advantages of irreversibility, resistance to imitations and sensitivity to init ial values,etc., are also discussed. Simulation results show that this chaotic H ash function based on extended chaotic maps switch has good one-way，weak collis ion property, better security than the chaotic Hash function based on single cha otic map, and it can be realized easily.