The invention relates to a folding type core muscle group alternating training device applied to physical education curricula and an operation method. When students train all parts in the physical education curricula in universities, large machines are always used, and the machines are complex in structure, large in size and high in price. The alternating training device comprises two main frame bodies (16), the two main frame bodies are connected through a connecting piece (20), each main frame body comprises a homocentric-squares-shaped framework (2), the front end and the rear end of the homocentric-squares-shaped frameworks are provided with lateral frames (14) respectively, each homocentric-squares-shaped framework is connected with one end of one rotating plate (21) through a rotary shaft (17), the other end of each rotating plate is provided with a top rod (5), the upper end of each top rod is provided with two fixing rings (4), one end of each fastening pin shaft (11) penetrates through a round hole of the corresponding homocentric-squares-shaped framework and located in a groove of the corresponding top rod, and a chest developer (8) is arranged between each rotating plate and the corresponding homocentric-squares-shaped framework. The invention provides the folding type core muscle group alternating training device applied to the physical education curricula and the operation method.