Abstract: The conventional mechanical properties, cross-sectional hardness gradient, microstructure, and grain size changes of Q690 low-alloy high-strength steel plate at different correction temperatures were studied using experimental comparative analysis. The results showed that at different correction temperatures, the Q690 test plate exhibited a decrease in strength and an increase in ductility, and the conventional mechanical properties of the test plate increased with the increase of correction temperature; The surface of the Q690 test panel shows softening zones of different depths, and as the correction temperature increases, the depth of the softening zone tends to deepen; The surface structure of the Q690 test panel exhibits varying degrees of recrystallization. In actual production, it is not recommended to use medium high temperature (600-800 ℃) flame straightening technology for low-alloy high-strength steel plates of Q690 and above grades.