The effect of different solution temperatures on the micro-substructure and γ' phase of GH4742 superalloy were studied by EBSD and TEM, and the mechanical properties of GH4742 superalloy were measured. The results show that the proportion of static recrystallization of matrix increased with increasing solution temperature in the range of 1080℃ to 1120℃, which resulted in the decrease of the proportion of low-angle grain boundaries from 13.2% to 3.2%; Meanwhile, the grains were significantly coarsened with a size increase from 11.0 μm to 111.6 μm, the proportion of Σ3 twin boundary increased from 13.2% to 58.6%. The volume fraction of the primary γ' phase in the matrix decreased evidently with the increase of the solution temperature, while the size of the primary γ' phase increased, and the volume fraction and size of the secondary γ' phase increased continuously, and that of the tertiary γ' phase changed little. The variety of strengthening contribution of γ' phase was small by different solution temperatures, and the strengthening increment caused by grain boundary strengthening plays determine role in the strength of the matrix. The room temperature strength of GH4742 alloy decreased dramatically with the increase of solution temperature, while the high temperature strength and rupture fracture time increased markedly. The GH4742 alloy solution treated at 1100℃ exhibits good mechanical properties at either room temperature or high temperature.