Abstract: To solve the problems of long construction period of existing reinforcement materials and poor adhesion with old concrete structures, three kinds of magnesium phosphate cement (MPC) concrete were prepared by modified magnesium phosphate cement, the difference of mechanical properties between MPC and the ordinary portland cement (OPC) concrete and the influence of different aggregates were studied. Contrasting with OPC concrete, MPC concrete prismatic specimens were prepared for uniaxial compression test. The experimental findings show that the peak strain of MPC concrete is obviously higher than that of OPC concrete, and with adding lightweight aggregate, the peak strain of MPC concrete increases further. Its modulus of elasticity is obviously lower than that of OPC concrete, besides, the modulus of elasticity reduces further due to lightweight aggregate added. The Poisson ratio is about 0.2 at the elastic phase, but the Poisson ratio of MPC concrete is higher than that of OPC concrete at high stress. After the inelastic phase, there are more internal cracks, and the final failure phenomenon is more abrupt and looser after failure. MPC concrete shows stronger brittleness than OPC concrete.