Abstract: Ultrasonic testing is difficult to detect flaws in grained materials because of the low flaw signal-to-grain noise ratio. In this paper, an ultrasonic imaging method based on a horizontal dual linear array (HDLA) setup is proposed. The two linear arrays are arranged on both sides of the surface of the area to be detected. One of the transducer arrays excites the ultrasonic wave, while the other records the data of each channel, and finally focused imaging is performed. Compared with the single array and the one-side dual linear arrays (DLA) setup modes, this method effectively reduces the interference of strong backscattered signals in grained materials and improves the signal to noise ratio (SNR) of images. The imaging experimental results on grained copper samples show that the imaging SNR of the proposed method is improved by about 5~10 dB compared with the other two modes of single array and DLA, when the flaw is close to the array. When the flaw is far away from the array the single array mode and DLA mode fail, however, the HDLA method can still identify the flaw. This method provides a possible scheme for ultrasonic testing of grained materials.