Abstract: This paper designs a high cost-effectiveness broadband millimeter-wave phased array radar, consisting of three components: high cost-efficient antenna array architecture with low grating lobes, wide and narrow band integrated transceiver link, low cost open reconfigurable backend, it has the characteristics of high cost-effectiveness, broadband wide-angle scanning, broadband digital beam forming(DBF) and backend commercialization, etc. In response to the amplitude-phase susceptibility characteristics of the millimeter-wave radar, a broadband amplitude-phase distortion compensation method was applied to calibrate the wideband amplitude-phase characteristics, the main-to-side lobe ratio of the high-resolution range profile(HRRP) was improved from 0.2 dB to 28 dB, achieving a range resolution of 0.05 meters. For the first time in China, a Ka-band millimeter-wave phased array radar was successfully employed to achieve continuous and stable tracking of typical low earth orbit(LEO) space targets, high-resolution inverse synthetic aperture radar(ISAR) imaging of the LEO was accomplished by using a Keystone transform-based quadratic term compensation imaging method.