In the ultra-low altitude detection mode of circumferential laser fuze, range gate compression was used to achieve the ability of anti ground clutter. In order to meet the requirement of accurate and stable height measurement based on ground echo, the characteristics of ultra low altitude ground echo of circumferential laser fuze were studied. The ultra-low altitude ground detection model of circumferential laser fuze was established. Based on the bidirectional reflection distribution function, the power equation in time domain of the ground echo received by the circumferential laser fuze was derived. The laser echo characteristics of the ground were calculated and analyzed under different conditions of missile flight altitude, pitch attitude and ground reflection properties. The results show that the inherent absolute error of height detection by circumferential laser fuze increases with the increase of detection distance, while the inherent relative error decreases. With the increase of pitch angle, the pulse width broadening rate of laser echo pulse increases. The larger the specular reflection component of the bidirectional reflection distribution function of ground, the more sensitive the ground echo power varies with the missile pitch angle. Theoretical support was provided for the anti ground clutter research of circumferential laser fuze under the condition of ultra-low altitude.