This study investigates the effect of the solution-treatment, with solution temperatures from 1494 to 1533 K, on the microstructure and mechanical properties of fine-grain (65 μm) CM 247 LC superalloy. Tensile tests reveal that the yield strength of the alloy after multi-step 1527 K/2 h solution-treatment exceeds that after 1494 K/2 h solution-treatment. Additionally, the alloy after multi-step 1527 K/2 h solution-treatment had a lower creep rate and greater rupture life than that after 1494 K/2 h solution-treatment. The improved mechanical properties are attributed to the high volume fraction of γ′ particles with the proper size and the refinement of carbides, which inhibit the gliding and climbing of dislocations.