Accelerating experimental method of wet-dry sulfate erosion was applied to investigate the law of concrete strength changing with time. By means of statistics and regression, functions of mean value and standard deviation of concrete strength were obtained to establish the probability model of compressive strength of high-performance concrete exposed to the sulfate environment. The results show that: under the sulfate exposure, the mean value of concrete compressive strength presents the relationship of quadratic polynomial with time ； the function presenting typical exponential growth can be used to express the relation of standard deviation of compressive strength with time.