This paper analyzes the reasonable slope for heavily loaded truck from two aspects, i.e. truck and ship respectively. Taking common heavy dump truck and general river ship as the research object, this paper analyzes emphatically the value of slope limited by climbing ability, downhill performance and design water depth.The results show that the range of reasonable slope is from 5.5% to 9%. The greater the truck weight, and the deeper the ship draft, the less range of choice on the rive slope, which even tends to a fixed value. Meanwhile, the length of the slope should be no more than 150m,and the speed of the vehicle should be controlled within 10km/h.