In present study, the creep behavior of (TiB + TiC+Y 2 O 3 )/α-Ti composite with C-1 and C-2 microstructure were investigated with applied stress of 200 MPa and at 650–700 °C. The steady state creep rate increased by an order of magnitude from 650 °C to 700 °C, and the C-2 microstructure shown worse creep performance compared to C-1 microstructure. The creep activation energy of C-1 and C-2 microstructure were 359.5 kJ/mol and 380.2 kJ/mol, respectively, which were higher than the lattice diffusion in α-Ti. And the less Q G due to coarse microstructure was responsible for its higher creep activation energy in C-2. In addition to cracks were observed at β grain boundary, α colony boundary, α/β phase boundary, they were also observed near the fracture TiB whiskers and near decohesion reinforcements. The cracks in C-2 were mainly concentrated near the reinforcement, while those in C-1 were mainly concentrated in the matrix part. Further analysis confirmed that the creep deformation mechanism of C-2 microstructure was controlled by reinforcements, but the creep deformation mechanism of C-1 microstructure was controlled by matrix microstructure. Summarily, the effect of reinforcement on creep deformation of (TiB + TiC+Y 2 O 3 )/α-Ti composite could be divided in two aspect: microstructure influence and the reinforcement itself. For reinforcement itself, it indeed affected the dislocation movement and creep fracture behavior, and then improved the creep performance. However, for microstructure influence, the fine grain (more grain boundary), coarsen microstructure (more equiaxed characteristics of α lamellar) caused more grain boundary slip to participate in creep deformation, which in turn deteriorated creep performance. In this study, the latter effect was somewhat bigger. • The steady state creep rate increases by an order of magnitude from 650 °C to 700 °C. • The creep fracture mechanism is dominated by reinforcements in C-2 microstructure, but by matrix in C-1 microstructure due to the distribution of cracks. • More percentage of grain boundary and fine microstructure in composite promote more creep deformation by grain boundary slip, which resulting in poor creep resistance.