Self-spin bodies have the disunification problem of flight movement and rotation representation that could induce attitude algorithms to generate attitude error. To address this problem, a double rotation representation is proposed in this paper and the cone angles are defined between the reference frame and the body frame. Then, the angular model based on the double rotation process is derived in detail for flight control, and an attitude algorithm with the rotation vector and the angle conversion for navigation are also provided. Simulation results show that the varying cone speed has a bigger effect than the varying half cone angle, and the double rotation representation can decouple the coning motion completely and has better accuracy than the three rotation representation. Moreover, a good resistance of the attitude algorithm with rotation vector against the varying coning motion is shown though the non-commutative error still exists.