The invention provides an ultrahigh monitoring method, an ultrahigh monitoring device and ultrahigh monitoring equipment based on a millimeter-wave radar. The method comprises the steps of receiving afirst reflection signal and a second reflection signal received by the radar; separately mixing the first reflection signal and the second reflection signal with a local oscillator signal to acquirea first intermediate frequency signal and a second intermediate frequency signal; acquiring M spectrum positions, radial distances dK between the tops of M target objects corresponding to the M spectrum positions and the radar, M phase differences corresponding to the M spectrum positions and included angles [beta]K between the direction of the radial directions and the principal axis direction ofthe radar; and acquiring heights of the M target objects corresponding to the M spectrum positions according to the vertical distance between the radar and the ground, [beta]K, the included angle between the principal axis direction of the radar and the vertical direction, the included angle dK between the principal axis direction of the radar and the common line of intersections of monitoring points and the ground, to judge whether an ultrahigh target object appears.