Blue sheep was selected as the object to test the variation of its limbs vertical ground reaction force by variable slope channel with built-in pressure plate, in order to supply bionic prototype for quadruped robots with excellent climbing performance. Results showed that the peak vertical force and the vertical impulse on the left and right sides of the front and hind limbs were completely symmetrical when the sheep walking on the flat ground. The symmetry index of the front limbs was 99.16% and 99.62% respectively, and the symmetry index of the rear limbs was 98.65% and 99.42% respectively. Along with the increasing of slope angle, the blue sheep adjusted the vertical force distribution to prevent lameness, which caused fluctuations in the symmetry index of the left and right hoof. When walking on flat ground, the forelimbs of blue sheep showed higher vertical force than the rear limbs. With the increasing of slope, the vertical force borne by the rear limbs gradually increased. The difference index on the left and right sides of the blue sheep limb has a similar change pattern on different slopes. The mean difference indexes on the left and right limbs of the blue sheep from 0 to 35 degrees were 1.298, 1.305 7, 1.174 4, 1.223 75, 1.017 5, 0.890 5, 0.777 8 and 0.753 5 respectively.