In order to solve the path conflict problem of automated guided vehicles in horizontal handling operations of automated container terminals, a path optimization method based on tempo-spatial network was proposed. For single transportation demand, firstly, the road network was discretized into grid network, and a tempo-spatial network which is updateable by time was designed. Secondly, the minimum of the completion time was taken as an objective, and a vehicle path optimization model was established based on the set of available road segments under tempo-spatial network. Finally, the shortest path algorithm was used on the tempo-spatial network to obtain the shortest path. For multiple transportation demands, in order to avoid conflicts between paths, the tempo-spatial network of the next transportation demand was updated according to the path planning results of the current transportation demand, and the path planning meeting the collision avoidance and congestion easing conditions were finally obtained through iteration. In the calculation experiment, compared with the basic shortest path solution strategy (solving algorithm P), the proposed method has the number of collisions reduced to 0 and the minimum relative distance always greater than the safety distance; compared with the parking waiting solution strategy (solving algorithm SP), the proposed method has total delay time of task reduced to 24 s, the proportion of delayed tasks and average congestion rate of road network significantly reduced, and the maximum reduction were 2.25% and 0.68% respectively. The experimental results show that the proposed method can effectively solve large-scale conflict-free path planning problems and significantly improve the operation efficiency of automated guided vehicles.