Disclosed are a method for measuring the level of muscle relaxation, a device thereof and an apparatus for measuring muscle relaxation, and the method respectively obtains the sampled values of the acceleration and angular velocity of the measurement site via an acceleration sensor and an angular velocity sensor or a speed sensor and an angular velocity sensor, in order to calculate the degree of muscle relaxation according to the sampled values of the acceleration and angular velocity. As the calculated results combine the sampled values of the acceleration and angular velocity of the measurement site, the accuracy of the calculated results is higher. Moreover, the measurement combines an acceleration sensor and an angular velocity sensor or a speed sensor and an angular velocity sensor, so that the apparatus for measuring muscle relaxation can be placed in any position of the measurement site without influencing the accuracy of the measured results.