The invention discloses a calculation method of optimal self-rotational angular velocity for fixed-axis rotation of a service spacecraft. The calculation method comprises steps of firstly carrying out Fourier transform on the measured gesture quaternion of an object to obtain three characteristic angular frequencies of object movement; using the filtering method to allow the estimation values of the angular frequencies to be quite accurate; and finally, multiplying the characteristic angular frequency with the biggest effect with 2 to obtain the optical angular velocity of the rotation of the service spacecraft. According to the invention, through the designed self-rotating angular velocity, the service spacecraft is allowed to rotate, so the relative angular velocity and the relative linear speed between the service spacecraft and the object can be effectively reduced, load during capturing of a mechanical arm is reduced and safety of on-orbit services in the space is improved; and in addition, although the service spacecraft carries out fixed-axis rotation, the designed self-rotating angular velocity is not only defined in objects carrying out fixed-axis rotation, so for objects rolling over along the three axes, the relative angular velocity can be also effectively reduced.