In order to evaluate the stability of the slope where the piers of the bridge across the canyon are located, based on the S253 Tuzat Bridge project of Baojing Qianling to Ramsha highway, combined with geophysical exploration, drilling and numerical simulation methods, the overall and local stability of the slope in the deep V canyon section is analyzed and studied. The results show that: 1) the rock mass on both sides of the Tuzha river is in a state of compression, the plastic zone does not form a through slip path, and the rock mass as a whole is in a basically stable state; 2) the joint cracks on the Baojing bank of the Tuzhate bridge have little impact on the stability of the slope, and the impact on the upper bridge structure is negligible; 3) the instability mode of the slope of the Baojing bank is not a simple arc or linear sliding, but a sliding zone with a certain thickness formed by various factors. The results can provide references for the stability assessment of slopes similar to deep "V" canyons.