Effects of different heat treatment regimes on the precipitate behavior and grain growth of low expansion superalloy were studied. The experimental results show that the size of Laves phase increases gradually but the grain size does not grow when under the Laves phase precipitation peak temperature ranges from 980℃ to 990℃. After holding at 1000℃~1040℃ for 1h, Laves phase began to dissolve, and the grain size gradually grew to grade 4, 3.5, 3 and 2. Therefore, in the process of hot working, to avoid the growth of grain size, the thermal deformation temperature should not exceed 1010℃, or the deformation at 1000℃ and holding time should not exceed 1h. Laves phase content at grain boundary has little effect on the properties of the alloy, but the grain size has a great effect on it.