The crux of injection mold production is scheduling, which should be made before the mold manufacturing. Generally, a mold part has some operations subject to certain sequence constraints. Furthermore, some operations have to satisfy process combination constraints with one or more other operations. The expression method of operation constraints is studied. If genetic algorithm is employed to solve scheduling problems in injection mold manufacturing, invalid chromosome representation during the computing period of population initialization and the crossover, mutation will generated unavoidably. An adjustment algorithm is proposed to ensure the validity of chromosome representation. Any chromosome representation based on operation or workpiece could be adjusted to a valid operation sequence by this algorithm. The feasibility of the algorithm is validated by computing cases.