Cross docking is an innovative system that products are distributed to the distribution centers via trucks, consolidated according to customer demands, and loaded into trucks to be delivered to customers. This study focuses on the truck-scheduling problem, which consists of assigning each truck to a door at the dock and determining the sequences. This study presents a mathematical model and a Simulated Annealing Algorithm for door assignments and truck scheduling in multi-door cross-docking centers. The objective of the model is to maximize of the total number of shipping products within working time period. The results of the mathematical model and the meta-heuristic algorithm are compared by generating different test problems.