Robot-assisted surgery is a significant advancement in contemporary medical applications, with force sensors playing a crucial role for this field. A snake robot with integrated force sensors can measure the force exerted on human tissues during surgery in human organs (bronchi, small intestine, etc.). In this study, a new type of capacitive force sensor was designed, which consists of two elastic parts and two rigid parts, and can achieve three-axis force sensing in robot-assisted surgery. According to the current simulation results using finite element method, the force measurement range of the force sensor can reach 5 N, the resolution is 0.05 N, and this force measurement range is the force that human tissues may endure in general surgery.