A one-way hash function algorithm is proposed based on the chaos mapping and multiplicative congruential method. The initial value of the system is generated by the pseudo-random sequence which is obtained through the multiplicative congruential method. the normalized ASCII of the plaintext is used as the initial value of the chaos mapping. After a variable-step chaotic digital quantification, 128 bit hash value is extracted from the systems. Theoretical analysis and simulation results show that the proposed method has better characteristics of irreversibility, collision resistance, anti-forgery, initial sensitivity and higher operation speed.