This research is about the analysis and design of variable capacity oil pump mechanism. The research has collected all relevant patent and literatures in various types of variable capacity oil pump. Classified and analyzed these papers by variable capacity oil pump mechanism and the way of motion. The results of the analysis as reference aspect for design a new type of variable capacity oil pump mechanism. Define the design requirements of variable capacity oil pump is the first thing to do. Then, conceive the main design requirements of mechanism in variable capacity oil pump mechanism. This study had used Pro/ENGINEER to draw 3D model to demonstrate the conception. Also this research has used Cosmos FloWorks in fluid analysis to verify the variation of flow in variable capacity oil pump mechanism for the studies of forthcoming manufacturing.