Abstract: Heat treatment has much obvious effect on microstructure and properties of joint in plasma arc "in-situ" welding of SiC_p/6061Al MMCs.Prior to annealing process, the improvement effect of solution treatment and aging on microstructures and properties of the joint of SiC_p/6061Al MMCs is better.Massive bulky phases Al₃Ti turn into short rod-like, and intergranular segregation is eliminated, and more homogeneous particles are obtained;heat affected zone is refined, and strength of the joint was improved to 245 MPa.