Aiming at the observable degree of gyroscope error coefficients for inertially stabilized platforms self-calibration system, a novel observable degree analytical method was presented according to the definition of observability. The highest order of measurement derivative in the expression of a state analytical solve was defined as the state observable degree. Based on this, the observability of inertially stabilized platforms self-calibration system was analyzed, highlighting the observable degrees of gyroscope error coefficients. The observable states of system were presented, and it was proved that the observable degrees of the gyroscope biases to sensitivity along the input axes were worst. Simulation results validated the correctness and validity of this approach, which provides a reference for the design of torquing scheme of inertially stabilized platforms self-calibration system.