Abstract: The influences of mix proportion of raw materials including fly ash, calcium hydroxide and chemical activator on the compressive strength were investigated by uniform design in order to produce high performance product with high volume of fly ash. A mathematical model described the relationship between compressive strengths and raw materials proportion was deduced using genetic algorithm and modified back propagation(BP) neural network. The optimal mix proportion was obtained by twice applications of genetic algorithm after introducing a penalty function in the model. The calculated compressive strengths at 7 d and 28 d were 35.61 MPa and 34.25 MPa, respectively, which were very close to the corresponding experimental results of 35.89 MPa and 34.10 MPa.