Abstract: The kinematic singularity principle of Single Gimbal Control Moment Gyroscope (SGCMG) systems is introduced and the survey of research progress in kinematic singularity is made.It is concluded that recognization of the singular principle is too simple to meet the need of nonsingular steering in SGCMG systems at present.It is pointed out that distribution and avoidability of singular points in gimbal space will be the main focus in the future.