DEFEND smart airbag helmets are designed to significantly reduce fatal injuries in motorcycle accidents and improve the rider's sense of safety and actual safety. The top of the helmet is integrated with a high-precision intelligent sensing device, which can detect deceleration and braking in real time, and automatically control the warning tail light on the back of the helmet, adjust the brightness and flashing frequency according to the braking intensity, and enhance the visibility at night and in bad weather conditions. The airbag system equipped at the bottom of the helmet quickly detects and triggers the airbag ejection when the vehicle rolls over or the rider is thrown out, fully protecting the head, neck and chest. The airbag system supports secondary use, and can be manually folded back to the original position after the gas is discharged, which is convenient for reuse.