Abstract: A fitness apparatus based on the principle of a flexible mechanical arm, includes a mechanical arm and a support part, the mechanical arm is connected with the support part, the end of the mechanical arm being provided with a mechanical interaction structure; also including a force feedback joint, a motion control module, a force field control module, a human-computer interaction module, and a human body motion posture analysis module. The present disclosure does not use any counterweights for strength control, allowing fitness training to be performed in a limited environment that could only be done in a professional environment in the past. The present disclosure can simulate a variety of huge fitness equipment, miniaturize and integrate large exercise equipment in many gyms, making strength training possible in a limited space, and also allowing gyms to save a large amount of equipment space and greatly improve their operational efficiency.