Based on single objective robust design of injection molding process, a bi-objective robust design model based on mean and standard deviation of molding quality and a multi-objective ant colonies algorithm with crossover and mutation based on Pareto optimization are proposed. Aimed at the craft parameters of plastic injection for the top and down shell of remote controller, a model of bi-objective robust design based on mean and standard deviation of warpage quantity is established with an example. And the model is solved by multi-objective ant colonies algorithm of crossover and mutation. The result shows that partial performances of algorithm are superior to that of NSGAII. The actual plastic injection was done by means of the parameters which were gotten by multi-objective robust optimization. The quality of plastic parts was high, and the fluctuation was small.