The invention provides a heavy-loaded stepless speed changer. The heavy-loaded stepless speed changer comprises a shell, an end cover, a driving shaft, a driving bevel gear, a driven shaft, a driven bevel gear, a speed regulating device, transmission wheels, a rotating disc and an output shaft; the driving shaft is in drive connection with the driving bevel gear, the driving shaft penetrates through the center of the speed regulating device to be arranged, the driven shaft is arranged on the lower portion of the speed regulating device, the driven bevel gear is fixed on the driven shaft, and the driven bevel gear is meshed with the driving bevel gear for transmission; each transmission wheel is in transmission connection with a transmission key of the driven shaft in a sliding mode in the axial direction, the rotating disc is arranged under the transmission wheels, and the surface of the rotating disc makes contact with the surfaces of the transmission wheels; the output shaft is fixedly connected with the rotating disc, the shell is arranged outside in a covering mode, a fist shaft hole is formed in the bottom of the shell, and the output shaft penetrates out of the shell through the first shaft hole; the end cover is installed at the top of the shell and tightly presses all parts in the axial direction, a second shaft hole is formed in the center of the end cover, and the driving shaft penetrates out of the end cover through the second shaft hole. The heavy-loaded stepless speed changer achieves heavy-loaded stepless speed changing transmission.