What should I do if I dance jazz and shake my body?

The reason why you sway is that your center of gravity is unstable. You should remember that the center of gravity of any dance is in the center of your body, between your legs, perpendicular to the ground. Once it deviates from the center, it will naturally become unstable. In addition, your strength must extend to the soles of your feet with the movements of your footsteps. So for your present situation, I think your basic skills are not solid enough. Before you practice dancing, you must consolidate your basic skills so that you can dance fast, steadily and charmingly.