The invention belongs to the technical field of sensors, and provides a joint angle measuring method and a joint angle measuring system. For the joint angle measuring device and the joint angle measuring method, micro attitude sensors are adopted. The attitude sensors are fixed to the limb at two ends of a movable joint in a pasting manner or in a manner adopting a bandage, and the limb movement attitude result measured by the attitude sensors is converted into the movement angle of the joint through a specific mathematical relation. The invention aims at providing the measuring mode which islow in cost, is flexible, and is free of the limitation of site requirements, with the measuring mode, the measurement precision in the prior art is improved, the user experience is promoted, and theproblems that the precision is poor and the device is expensive in the prior art are solved.