In order to make solid waste utilization of the large amount of waste cave slag produced during tunnel excavation, based on the engineering project of Wuyue high-speed WYTJ-07 bidding section, the produced metamorphic granite was adopted to prepare machine crushed gravel and machine crushed sand. The mix ratio experiment on the granite impermeable concrete was carried out, followed by revealing the influences of granite cave slag on the performance of impermeable concrete to determine the optimal mix ratio of C30P10 granite impermeable concrete. Experimental results show that, according to its mechanical properties and composition, the granite cave slag obtained from this tunnel site meets the requirement of preparing impermeable concrete. According to the slump degree, 28 d compressive strength and impermeability grade of different proportions of concrete, it was found that reducing the water-cement ratio and increasing the amount of admixture would effectively improve the working performance of granite impermeable concrete. When the water-cement ratio is 0.43 and admixture content is 1.1%, the performance of C30P10 granite impermeable concrete meets the requirements and it is the most cost-effective.