An improved multi-Agent Path Finding Algorithm based on Conflict Search Algorithm is proposed for the path planning problem of picking-delivery with mobile robot clusters in smart storage environment. In terms of the model, a mathematical planning model with the objective of minimizing the picking-delivery time and the invalid path ratio is established by using multi-carrier robots instead of KIVA robots. In terms of the algorithm, firstly a priority rule-based multi-intelligent conflict resolution acceleration strategy is proposed; then a single-robot picking sequence optimization algorithm based on dynamic planning is designed; finally an enhanced A* algorithm with the consideration of turning penalty is proposed to search for the optimal robot path. The experimental results show that the proposed model is superior to the KIVA system; the proposed algorithm can effectively shorten the picking-delivery time and reduce the invalid path time.