Car door or tail door unlocking opening method and device

The invention relates to a car door or tail door unlocking opening method and device. A Doppler effect wave source transmitting and receiving module 1 is arranged on the bottom of a car door 11 or a tail door 10 for continuously transmitting detection waves 13 and receiving reflection waves 14 formed in a way that the detection waves are reflected by an object, the state is judged by utilizing the Doppler effect principle, a sensing area is a space between the bottom of the car door 11 or the tail door 10 and the ground, and the car door 11 or the tail door 10 can be unlocked and opened by a foot 12 through the movement of the foot 12 in the area.