The cylindrical gear in power window motor assembly is important to doors of automobile. This study is performed for purpose of getting a manufacturing technique instead of large quantities import and small cavity mold production. This multi-cavity cylindrical gear is produced under five procedures. The first, mold design of massproduction, the second, making a CAE model for mass-production, the third, manufacturing of sample mold, the fourth, trying-out and measuring of 3 dimensional design, the fifth, acquisition of data analysis and mold modification. Among them, analysis of mass-production using CAE, design and manufacturing of multi-cavity are successfully performed. In the results, it is concluded that mold for one gate and six cavity based on hot-runner is suitable for making a cylindrical gear.