The functioning of modern distribution centers is impossible without the effective organization of the work of mobile material handling equipment, which is the main means of processing cargo flows in warehouses and directly affects the costs and time of warehouse operations. The article proposes the mathematical model for determining the optimal number of forklifts in the distribution center based on integer programming using the open queuing network model. The model reflects the peculiarities of the technological process of cargo handling in the distribution center and the participation of forklifts in it. Given the impossibility of using exact optimization methods because of the type of the objective function, the heuristic method is proposed for solving the problem, which allows for avoiding the complete enumeration of solutions and finding the optimal number of forklifts in a short time, considering different scenarios and operating modes of the distribution center. The advantage of this heuristic algorithm is its ability to determine the optimal number of service channels in high dimensional open queuing networks. The minimum of total service costs, which include operating costs for the maintenance of forklifts and cargo flow handling costs, were used as an optimization criterion. The model is an effective tool for decision making when equipping distribution centers with mobile material handling equipment.