Synthetic aperture (SA) imaging algorithm, which combines sub-aperture elements to form high resolution image, can improve image quality in vivo ultrasound image. However, large computation resource is generally required for the implementation of SA. In this paper, we propose a parallel structural design for SA imaging algorithm that can be realized in Field Programmable Gate Array (FPGA), so that light weight and miniaturized design can be achieved. The proposed design has been validated by MATLAB and was employed to construct a high resolution ultrasound imaging from the raw data of 128 array transducer elements. The processing time is about 2.6ms theoretically, which should be alright for usage.