[Purposes]The paper aims to explore the problem of soil slope in stability of canal caused by unreasonable excavation. [Methods]Taking the incised soil slope of Centianhe trunk canal as an example, its construction process was restored by FLAC^3D numerical sim- ulation, the excavation design scheme was reviewed, and the failure mechanism of traction landslide induced by slope excavation was analyzed. Aiming at the instable soil slope, two reinforcement treatment schemes were put forward,namely the scheme 1(slope anchoring support,canal lining)and the scheme 2(slope anchoring, hidden culvert replacing open channel), and the effectiveness of the treatment measures was analyzed.[Findings]The stability of the slope reinforced by the scheme 2 is obviously better than that of the scheme 1, the safety factor can reach more than 1.18 under the most unfavourable condition,and the overall safety of the slope can be guaranteed. Moreover, the influence of slope excavation on surface deformation can be minimized, and the research results can guide the smooth construction of slope in the later period. The pulsating grouting was simulated based on TOUGH2, the grouting scheme and parameters were determined by finely simulating the grouting process,and the strength parameters were modified by interpolation in FLAC^3D in the form of mass fraction. The strength reduction method was used to calculate the safety factor of the excavated slope to determine the pre-reinforcement design scheme.[Conclusions]For similar slopes, they should be pre-reinforced before excavation, and the pre- reinforcement measures should give priority to the pulsating grouting method to improve the overall stability of the slope. The slope safety factor reaches more than 1.50 after using the hole-layout scheme of 3 rows of holes, 2 m hole spacing and 8 m hole depth.Compared with the direct excavation, the scheme can effectively reduce the risk of slope collapse, and the research results can be used as a reference for similar projects