A continuously variable transmission device with a low shift transmission pulley train includes a unidirectional transmission device installed between the input shaft and output shaft of the continuously variable transmission device. During high load operation, when a rotating speed of the driving pulley of the low shift transmission pulley train is lower than that of the input shaft in the same rotating direction, the rotational kinetic energy of the input shaft is transmitted through the unidirectional transmission device and the low shift transmission pulley train to drive the output shaft and further to drive the load.