The invention provides an energy-saving vehicle braking device and method. The device comprises a transmission part, an output and input part and an accessory part, wherein the transmission part comprises a sun gear, a planetary gear, an inner gear, a power gear, a semi-axle shaft sleeve, a brake drum, a brake synchronizer, a release synchronizer, a front bearing and a rear bearing; the output and input part comprises a transmission shaft, an output and input gear, a transmission shaft front bearing, a transmission oil seal, an output and input gear key, a flat gasket, an output and input gear bolt, a front cover and a brake drum oil seal; the accessory part comprises a casing supporting a half shaft and a Hall wheel speed sensor. The energy-saving vehicle braking device is reasonable in structure design and is safe and reliable to use, the problems of energy waste, danger and high probability of damage to tires and pavements of an existing braking device adopting the friction principle are fundamentally solved, most energy in the braking process can be recovered and utilized, the drag slip and sideslip phenomena of a vehicle are prevented, and traffic safety is ensured.