In order to study how to reduce the quality of the bucket on the premise of meeting the strength requirements, a bucket lightweight design method based on continuous digging trajectory and limiting digging force was proposed. Based on the continuous trajectory theory, when the arm of the digging robot was in the main excavation area, the four tracks excavated alternately by the bucket and rod hydraulic cylinder were selected as the research premise, and the numerical variation law of the limiting digging force on the continuous trajectory was calculated and analyzed. The bucket parametric model was established by using APDL language, and the variation law of bucket structure strength was studied by taking the limiting digging force as the external load. Taking the bucket quality and stress as the optimization goal, the bucket structure optimization model was established, and the genetic algorithm method was used to optimize the bucket. The results show that the stress and deformation of the bucket during the bucket hydraulic cylinder excavation is obviously larger than that of the rod digging. After optimization, the quality of the bucket is reduced by 527%, and the maximum stress is reduced by 623%, which verifies the feasibility of the optimization method.