Aiming at the problems of expansion and cracking that may occur in high-strength concrete(HSC) serving in long-term humid or water environments, the influence of further hydration on HSC property was studied by simulation test. Firstly, the influence of slag powder content on the physical and mechanical properties and permeability of HSC was discussed. Secondly, the influence mechanism of further hydration on the strength of concrete with or without slag powder was analyzed. Finally, the influence of loading degree on the strength of pre-damage concrete was expounded. The results show that the variation ranges of the compressive strength and ultrasonic sound velocity value for concretes with or without slag powder are both not obvious, while the decreased degree of the electric flux first decreases and then increases with an increase in the slag powder content. The decreased degree of compressive strength first increases and then decreases with an increase in loading degree and moreover, the increase in splitting tensile strength shows an increasing trend. The further hydration products continuously fill the initial cracks of pre-damage concrete. When the internal space of concrete is not sufficient to accommodate the products, the volume expansion of products leads to the formation of microcracks and a decrease in strength. However, during the late stage of further hydration, the new microcracks provide channels for the entry of extraneous water again, and the new products fill its internal pores and defects. This ultimately causes an increase in strength. The influence laws of slag powder and loading degree on the performance of HSC under further hydration effect are put forward, which provides some reference for the performance evaluation and design of HSC.