A real-time measurement system for mechanical parameters of rock slag during excavation includes a rock slag conveyor belt configured to convey rock slag; cleaning device, located on both sides of the rock slag conveyor belt, configured to clean the rock slag; an image acquisition device, located behind the cleaning device and on both sides and above the rock slag conveyor belt, configured to collect images of rock slag; an on-site loading device, for conducting on-site mechanical loading procedure on the rock slag to obtain on-site mechanical parameters. The on-site loading device includes a loading bottom plate, a push plate and a pressure head. The loading bottom plate is provided with a loading area. The push plate is located on the loading bottom plate and pushed by a pushing mechanism to push the rock slag.