[Purposes]The paper aims to explore the influence of fly ash content on concrete compressive strength in sulfate saline soil area to provide some reference for practical engineering construction. [Methods]Four groups of 48 standard cubic concrete test blocks with side length of 150 mm were embedded in the test site, whose fly ash contents were 0%, 10%, 15% and 20%, respectively. The compressive strength was measured regularly and the microstructure was analyzed through scanning electron microscope. [Findings]The compressive strength of concrete test blocks with different mix proportion increases to a certain extent at the early stage of erosion. With the increase of erosion time, the compressive strength begins to decrease gradually. Combined with orthogonal test analysis, it is considered that the best content of fly ash is 10%. The ettringite crystals formed by the combination of SO^2-₄ penetrated into the concrete and hydration products gradually increase at the later stage of erosion, and the ettringite absorbs water and expands, resulting in the expansion of micro cracks and affecting the overall compactness of the structure.The General Model Gauss function in MATLAB was used to fit the test data of early concrete compressive strength. The results show that the fitting effect is good. [Conclusions]For the research on the durability of fly ash concrete in sulfate saline soil area, a variety of test methods should be used to analyze the changes of mechanical properties of concrete, and the combination of numerical simulation and test results should be strengthened to make a better prediction of the compressive strength of concrete