The invention provides an automatic starting, stopping and braking device of a pumping unit. The automatic starting, stopping and braking device comprises a brake base and further comprises an electrically controlled brake system and a control box. The electrically controlled brake system comprises an electromagnet, an armature, a transmission pull rod, a reduction gearbox brake block, a reduction gearbox brake rod and a self-locking device, wherein the electromagnet is arranged on the brake base; reset springs are arranged on the two sides of the electromagnet; the armature is arranged over the electromagnet; the two ends of the armature are connected with the reset springs on the two sides of the electromagnet; the reduction gearbox brake block is connected with the reduction gearbox brake rod; the reduction gearbox brake rod is connected with the armature through the transmission pull rod; the transmission pull rod is provided with the self-locking device; the control box integrates a controller and a distribution box. A station control platform can accurately control the stopping position of the pumping unit, the digital control level of an oil field is improved, labor intensity is relieved, and field safety risks are reduced.