A maximum muscle strength measuring method implemented in a muscle training device, the muscle training device including a drag unit, an operation display unit, and a control unit, the method comprising the steps of: a. selecting a muscle of a user or a motion to be measured through the operation display unit; b. setting up a resistance value through the display unit and generating at least one test resistance value based on different proportions of the resistance value; c. generating at least one drag force based on the at least one test resistance value; d. overcoming the at least one drag force by the user steadily holding the drag unit, and measuring a steady operation time of the drag unit by a position sensor and the control unit; e. judging whether the drag unit meets a condition for generating a muscle strength value, wherein the condition for generating the muscle strength value is judged based on the steady operation time of the drag unit; f. obtaining a maximum muscle strength coefficient based on an accumulative number of times that the user meets the condition for generating the muscle strength value continuously in the step e, and calculating the muscle strength value via dividing the resistance value by the maximum muscle strength coefficient; g. generating a test drag force, for the drag unit to exert or resist, based on the muscle strength value; h. lowering the muscle strength value by a lowering proportion if the user is unable to overcome the test drag force and meet the condition for generating the muscle strength value, and returning back to the step g; i. raising the muscle strength value by a raising proportion and returning back to the step g if the user continuously overcomes the test drag force to complete more than one time of the measurement and meets the condition for generating the muscle strength value; and j. outputting the muscle strength value as the maximum muscle strength if the user is able to overcome the test drag force and meet the condition for generating the muscle strength value only once. a. selecting a muscle of a user or a motion to be measured through the operation display unit; b. setting up a resistance value through the display unit and generating at least one test resistance value based on different proportions of the resistance value; c. generating at least one drag force based on the at least one test resistance value; d. overcoming the at least one drag force by the user steadily holding the drag unit, and measuring a steady operation time of the drag unit by a position sensor and the control unit; e. judging whether the drag unit meets a condition for generating a muscle strength value, wherein the condition for generating the muscle strength value is judged based on the steady operation time of the drag unit; f. obtaining a maximum muscle strength coefficient based on an accumulative number of times that the user meets the condition for generating the muscle strength value continuously in the step e, and calculating the muscle strength value via dividing the resistance value by the maximum muscle strength coefficient; g. generating a test drag force, for the drag unit to exert or resist, based on the muscle strength value; h. lowering the muscle strength value by a lowering proportion if the user is unable to overcome the test drag force and meet the condition for generating the muscle strength value, and returning back to the step g; i. raising the muscle strength value by a raising proportion and returning back to the step g if the user continuously overcomes the test drag force to complete more than one time of the measurement and meets the condition for generating the muscle strength value; and j. outputting the muscle strength value as the maximum muscle strength if the user is able to overcome the test drag force and meet the condition for generating the muscle strength value only once.