The invention discloses a robot collision detection method based on a second-order generalized momentum observer. The method comprises the following steps: firstly, constructing a robot kinetic model, and recognizing kinetic parameters; secondly, establishing a generalized momentum observer, determining a gain coefficient, establishing a friction model in a targeted manner, and identifying model parameters; and thirdly, a second-order generalized momentum observer is established through a second-order damping model, a PD regulator is connected in series on the basis of the second-order damping model, and a threshold value is set. According to the robot collision detection method based on the second-order generalized momentum observer, adjustable parameters are increased, system controllability is improved, short transition time is easier to obtain, system collision detection delay is reduced, and the application value is high. The method can be applied to the collision detection technology.