To enhance production and energy-saving efficiency, injection molds designed with numerous cavities are preferred. As the number of cavities increases, so too does the complexity of the task of balancing the flow paths. Despite the geometrically systematic delivery system and cavities, asymmetric branching of flow paths, uneven viscous heating, and cooling variation exist in the molten flow to the cavities. These variations substantially reduce the benefit of a multicavity mold. In imbalanced multicavity molds, the ideal processing conditions for the cavities that are filled first may differ from those for late-filled cavities. As a result, the processing settings on the press are compromised. This narrows the processing window and makes quality control more difficult. A new technique based on fuzzy logic was developed to control the filling time of each cavity automatically. Base on the reasoning of the fuzzy rule base and using the LabVIEW program, the temperature of a hot runner compensation mechanism was constructed built to control the filling time of each cavity. Eight-cavities preform mold was constructed with which to implement this module realization, and experiments were conducted. The results revealed that the difference in the time taken to fill each of 8 cavities was reduced from 0.14 s to 0.053 s (62.1% reduction). This technology integrates mold design, process optimization, and rapid smart control. It effectively improves the quality and consistency of injection-molded parts.