The large number of array elements leads to the high cost and high design complexity of forward-looking array SAR system. How to obtain higher imaging quality with fewer array elements is a difficult problem for forward-looking array SAR system. According to the quality requirements of system imaging, combined with beam scanning and grating lobe suppression technique, a design method of sparse transmitting and receiving antenna array is proposed. Theoretical analysis and simulation results show that the method can effectively reduce the number of array elements and improve the signal-to-noise ratio of the system, and has a certain application value.