The invention relates to a multi-factory cooperative scheduling optimization method during equipment manufacturing. The method is a multi-agent and improved ant colony algorithm-based scheduling model and algorithm and is characterized by comprising the following steps of: establishing a multi-agent-based scheduling system model framework; introducing a genetic algorithm into the ant colony optimization process and establishing the improved ant colony algorithm to support the scheduling decisions of the agents and determine production equipment, a processing order and processing time for each workpiece task of a manufacturing system. The method has the advantages of optimizing the target, shortening the completion time of the workpiece task, improving the utilization rate and production efficiency of the equipment along with simple operation, high convergence rate and high convergence performance; moreover, the method is suitable for a multi-factory cooperative manufacturing process and the common production process of the common manufacturing enterprise as well, realizes coordination among a plurality of manufacturers producing the same product during the manufacturing by optimal task allocation and scheduling, has a wide application range and is suitable for popularization and application.