Statically deployed marine ranching WSN is prone to the energy hole in the region close to the sink node during multi-hop data transmission. A reliable communication path planning method for the mobile sink node based on improved ant colony algorithm is proposed. First, for the traditional ant colony algorithm, non-uniform distribution of initial pheromone concentration is used to solve the problem of blind search at the initial stage of the algorithm. The heuristic function value in the transition probability function is modified and the crowding influence factor is added to avoid deadlock and speed up the convergence. In order to ensure the convergence ability of the algorithm at a later stage, an improved update rule for the pheromone is used. Secondly, LEACH protocol is used to cluster the network. According to the location of the cluster head node and the communication coverage area, the ergodic point set of the mobile sink node is constructed. Finally,the path planning problem of the mobile sink node is regarded as the traveling salesman problem, and the optimal path of the mobile sink node is obtained by the improving ant colony algorithm and the constructing backbone node set. The simulation results show that, at the scale of 275 network nodes, compared with other algorithms, the path length of PMRM is reduced by 41.9%, 20.3% and 30.4%, the data transmission delay is reduced by 42%, 38.5% and 46.7%, and the network throughput is increased by 10%, 10.6% and 16.4%. The superiority of the method is verified. The proposed method can effectively optimize the reliability of marine ranching WSN data reception, the energy consumption characteristics of the network and the life cycle of the network by introducing the mobile sink node and exploiting the rationality of their mobile paths.