A weight training method, a weight training apparatus and a weight training system are provided. In the method, a weight of a load of a user operating the weight training apparatus is detected by a load sensor, a motion of the load is detected by an activity sensor, and thereby an operation power of the weight training apparatus is calculated. A force applied by the muscle portion when the user operates the weight training apparatus is detected by at least one biophysical quantity sensor disposed on at least one muscle portion of the user and used to calculate an energy power consumed by the user. An exercise efficiency value of the user is calculated by using the energy power and the operation power, and the user is prompted to adjust an operation performed on the weight training apparatus when the exercise efficiency value drops beyond a preset ratio.