Soil corrosion has a significant influence on the mechanical properties of buried pipelines and is considered the primary cause of pipeline damage. In this study, a series of soil solution corrosion tests wee conducted on steel pipes specimens to investigate their corrosion behavior and mechanical performance degradation under various soil pH environments. The steel pipe specimens were buried in soil with different pH levels. The pipe specimens were then subjected to different tests to evaluate their mechanical properties in order to comprehensively analyze the relationship between corrosion behavior and mechanical performance degradation of Q235 pipes in soils with different pH levels. The test results indicate that: (1) the equivalent corrosion depth of Q235 pipes in soil corrosive environments follows an empirical equation in the form of a power function, with the corrosion rate gradually decreasing as corrosion time increases; (2) the reduction in soil pH significantly promotes the growth of local pitting, gradually developing from pitting to general corrosion; and (3) the mechanical performance of Q235 pipes is significantly affected by soil corrosion. The degradation coefficients of various mechanical performance indicators show linear degradation with increasing corrosion rate. The degradation rate of elongation after fracture is much higher than that of other mechanical performance indicators. It was also found that for the same corrosion rate, the degree of mechanical performance degradation of pipes in acidic soil is much greater than that in alkaline soil.