The utility model belongs to the technical field of a robot mechanism. More specially, the utility model relates to a high speed three freedom parallelly connected robot arm which is composed of an upper platform, a lower platform and branches. Three branches are parallelly connected and installed between the upper and the lower platforms which are triangular. A ball pair on the three branches is positioned between a rod piece A and a rod piece B. The rod piece B is connected with a rod piece B through a movable pair. The rod piece C is fixed on the lower platform. The utility model has the advantages of lightness and high stiffness, and is suitable for high-speed movement.