Abstract: Aiming at the problems that linear array is poor isotropic and limited effective aperture of semicircular array in forward-looking sonar,an optimized structural design method of arc receiving array is proposed.According to different extent of imaging sector,the central angle of arc receiving array is designed to make all elements participate in beamforming of all directions.The far and near-field focusing model of arc receiving array is established,and the directivity function of arc receiving array is derived.Calculate the radius of arc receiving array with the best beam performance according to the threshold condition of the boundary beam grating lobe.The comparison of the beam performance at different sector extent of arc array,linear array and semicircular array show that when the view extent is between 900 to 1300,the main lobe performance of the arc receiving array is improved by 8%,the grating lobe level of the boundary beam is optimized by 4%.The comparison of simulation images with the view extent of 120°and depth of 100 m show that the cross-directional resolution depth is increased by 20 m and 45 m compared with linear array and semicircular array,the parameter storage capacity is only 2.7%of the linear array.The arc array has the advantages of large effective aperture and isotropic beam,which can effectively improve the detection performance of forward-looking sonar system and reduce difficulty of algorithm implementation.