<p>To improve the reliability and sensitivity of multi-level relay protection in distribution networks with distributed power sources, this study designs an adaptive setting strategy optimization method. This method fully analyzes the impact of distributed generation access on the dynamic characteristics of multi-level relay protection in distribution networks. By combining the overcurrent characteristics of multi-level relays with the operational principles of multi-level relay protection, the optimization objective function and constraints for the adaptive setting strategy under distributed generation integration are established. An improved Harris Hawk optimization algorithm is used to solve the objective function, obtaining an optimal multi-level relay protection setting strategy with the shortest setting time. Test results show that after applying the multi-layer relay protection adaptive setting strategy proposed in this paper, optimization schemes with good diversity can be obtained, which can effectively reduce the current difference of each line in the experiment, and the lowest can be reduced to 28A; The sensitivity of the relay protection device is 1.60 when the shortest length of the distribution network line is 6km, and 1.40 when the longest length of the distribution network line is 56km; After optimizing the multi-level adaptive setting of relay protection, 77.8% of the total length of the line can achieve adaptive current protection settings and accurately complete protection actions in case of faults.</p>