This paper discusses methods of quadruped stability control, and introduce some new examples with inertial assist system, where high speed spinning wheel produces a gyro torque to keep whole robot stability. One example shows commercial gyro stabilizer is simply attached on the body and make a trot walking stability. Second one has an actuator to rotate stabilizer. The third uses simple wheel with axis tilting actuation. Later two can make a pace walk which needs more torque to stabilize. These stability control methods have an advantage that no landing point arrangement is needed, where sometimes arrangement can not be executed because of terrain conditions. Also, the body does not make an acceleration to produce a dynamic stability, which means the robot can go straight without any shaking motions.