Abstract: To improve the anti-interference capability of automotive radar, a microstrip array antenna with high gain, low sidelobe, narrow beamwidth and easy integration is designed. The bandwidth of the antenna is improved by the slot-loaded technique, which adopts a series-parallel hybrid feed network, between each array element is used to achieve unequal amplitude and in-phase by using the Dolph-Chebyshev distribution, effectively suppressing the antenna sidelobe level and achieving a higher gain with fewer array elements. Measured results indicate that the array antenna impedance bandwidth ranges from 23.73 to 24.56 GHz, with a maximum gain of 22.73 dBi. At the resonance frequency, the sidelobe level for the E-plane and H-plane are −21.23 dB and −22.16 dB, respectively, demonstrating good consistency between the measured and simulated results. The antenna is reliable and compact, making it suitable for 24 GHz automotive radar systems.