Abstract: In order to obtain the effects of different amounts of metakaolin on the physical, mechanical properties and hydration characteristics of concrete, basic physical and mechanical tests of metakaolin concrete and concrete hydration performance tests were carried out. The results show that the proper addition of metakaolin instead of concrete cement admixture can better improve the mechanical properties and working performance of concrete. However, with the increasing content of metakaolin, the cement content inside the concrete will decrease and the chemically bound water inside the concrete will decrease. So that the heat and rate of hydration are reduced, and the content of calcium hydroxide generated by the hydration reaction is reduced. By combining the XRD pattern analysis of metakaolin after hydration, it can be known that the peak value of the XRD pattern of ettringite is the most significant when the content of metakaolin is 15%. This is consistent with the content of metakaolin that is obtained in the early stage to achieve the best mechanical properties of concrete.