Abstract: There have many limitations in the traditional fluid-projectile-assisted injection molding (FPAIM) process. Therefore, the evolution of the FPAIM technology was discussed in detail. The FPAIM molding for the pipes with ends openings, closed voids and branches were realized by adopting proper means. The pipes with variable cross-section, the efficient molding and the removal of projectile were achieved by selecting a proper projectile shape, projectile material and projectile formation method, the stable penetration of projectile. A stable penetration of projectile could be obtained by the modification of the mold, resulting in a uniform wall thickness. The application of FPAIM process and the functions of FPAIM parts could be expanded when this technology was used for the formation of elastic hollow pieces in combination with other processes.