Abstract: According to the design requirements and technical specification for the axial support of the primary mirror of the 2-m Ring Solar Telescope (RST), a Bellow-based Pneumatic Force Actuator (BPFA) was developed and comprehensive tests were carried out. A metal bellow was used as a tensile core pneumatic cylinder of high-strength and high-elasticity. With a linear bearing as the guide for force output, the BPFA integrated a pressure sensor to force detection and feedback. The convenience of installation, adjustment and maintenance have also been taken into consideration. The test results shows that the output pushing force of the BPFA is up to 200N with a full scale linearity error less than 2%. And the closed-loop correction output force falls within the range of ±0.3N, with a force resolution of 0.23N.The tests have verified the feasible design by its clear principle, simple structure, easy installation and maintenance of the pneumatic force actuator. The BPFA meets the axial support technical requirements of the ring primary mirror of the 2-m RST. The development and research of the BPFA paves a concrete way for the improvement of its detailed design and the optimization of the axial support system for the ring mirror, it shall also provide a reference for other precision optical mirror support systems.