Terahertz (THz) imaging has wide applications, including biomedical imaging and security inspections. With the development of modern information technology, portable terahertz imaging devices are demanding. This paper introduces a broadband terahertz wave imaging system based on CMOS process technology. The system includes a detector, two sets of Teflon lenses, a three-dimensional high-precision translation stage, and a terahertz source. The detector uses a standard 180 nm CMOS process and achieves a wide frequency range of 0.14–1.1 THz by combining outputs from narrowband detectors with different center frequencies. To save space, the narrowband detectors are designed with a nested configuration, where high-frequency narrowband detectors are sequentially placed inside low-frequency narrowband detectors. Each detector has an area of only 200 × 200 μm2. At 688 GHz, the detector achieves optimal performance, with a noise equivalent power (NEP) of 25.1 pW/Hz1/2 and a current responsivity (Ri) of 256 mA/W. The system is capable of acquiring clear scanning images under terahertz illumination. Experimental results demonstrate imaging capabilities for metal and metal within envelopes at frequencies of 225 GHz, 305 GHz, and 688 GHz, highlighting the potential of this technology in practical applications.