Abstract: In order to meet the application requirements of millimeter wave radar, a millimeter wave radar array antenna operating at 24 GHz is proposed in this paper. The antenna is a planar array composed of eight 1×8 microstrip series-fed linear arrays, and each linear array adopts the form of center feed which solves the problem that the beam of the traditional series-fed array deviated from the normal of the array. The substrate integrated waveguide is used to design a low loss feed network, which is arranged on a two-layer dielectric substrate with the radiating patches, and the area of the antenna is greatly reduced. In addition, Taylor synthesis method is used to optimize the width of the array element and the distribution ratio of the power divider, so as to optimize the sidelobe levels of both E and H planes. The measured results indicate that the impedance matching band of | S11 | <-10 dB in the frequency band from 23. 7 GHz to 24. 2 GHz. The relative bandwidth is about 2. 1% and the maximum gain of the antenna is about 21. 1 dB. The sidelobe level of the antenna on the electrical field plane is less than -20 dB and less than -23 dB on the magnetic field plane, and the overall efficiency is about 69%.