Highway bridges are primarily reinforced concrete structures. They have multilayer steel mesh sheets, corrugated pipes, and steel strands inside. As a result, detecting defects in bridge concrete structures requires high technical expertise and can be challenging. This article presents a new device of ground-penetrating radar (GPR) designed specifically for highway bridge inspection. It employs antenna array technology, multichannel radar control technology, and real-time 3-D data acquisition and display technology to achieve reliable detection of various concrete structures commonly found in bridges. Using a 1.3 GHz central frequency antenna array and a multichannel control unit, the system enables simultaneous surveying along five lines, the detection depth can exceed 600 mm in concrete. This significantly enhances detection efficiency. By employing specialized software processing, the detection results are presented in a specific and visually comprehensive 3-D format. Moreover, the system provides 3-D slice images from any position and direction, facilitating the interpretation of detection results for various targets, including reinforcement layout, protective layer thickness, corrugated pipes, steel strands, and other quality defects. It provides advanced and reliable technical means for construction quality control and bridge health monitoring of highway bridges. The results indicate that the device performs well not only in controlled experimental environments, but also in real-world bridge structure environments.