Objective: To comprehensively observe the changes of physical quality and body composition of fitness enthusiasts after scientific resistance training. Research methods: This paper mainly adopts the experimental method, with 30 fitness enthusiasts who have a certain training basis as the experimental subjects, including the experimental group of 15 people, the control group of 15 people, the experiment time is 63 days. Results: In terms of body composition, subjects’ body weight, body fat percentage and skeletal muscle content had obvious benign changes; In terms of physical fitness, the subjects’ physical fitness was improved under the intervention of the health management plan (evaluated by three fitness items: barbell squat, barbell hard pull and barbell bench press), and the weight of the barbell used in training was improved to varying degrees. Conclusions and Suggestions: Controlling body fat is beneficial to skeletal muscle growth, scientific diet can improve body strength, regular rest and exercise can effectively reduce BMI and WHR.