1. A multi-objective semiconductor product capacity planning system, comprising: a data input module, accepting inputs of machine information, product information and order information, the machine information defining a plurality of production stations and a capacity limit of the plurality of production stations, the product information defining a plurality of product categories and a production cost of the plurality of product categories, the order information defining a demand quantity of order for a plurality of customer orders and a product price; a capacity planning module, receiving input data from the data input module, coordinating the demand quantity of order with the machine information and the product information to plan a satisfied number of order to satisfy the capacity limit, determining the satisfied number of order by a capacity allocation proportion of order to decide a capacity utilization rate of each of the orders and a satisfied priority of order to arrange a production sequence of each of the orders, combining the capacity allocation proportion of order and the satisfied priority of order as a resource allocation and transforming the resource allocation into a gene combination by a chromosome encoding method; and a computing module, receiving the gene combination from the capacity planning module, calculating the gene combination several times to generate a plurality of new candidate solutions by using a multi-objective genetic algorithm, sorting the plurality of new candidate solutions by using a plurality of planning objectives as evaluation criteria to generate a new gene combination, and repeating the calculation to form a candidate solution set until a stop condition is satisfied, transforming the candidate solution set into a plurality of suggestive plans and selecting one of the plurality of suggestive plans to arrange the production stations for manufacturing the product categories.