This paper presents an improved 0.18 μm CMOS detector linear array with high voltage responsiveness. Each pixel consists of high-gain on-chip antenna, high-coupling self-mixing power detection circuit and integrated voltage amplifier. The differential detection circuit uses the cross-coupling capacitance of the source differential driven FET, coupling the terahertz differential signal to the gate and the source of the FET, and enhancing the strength of the self-mixing terahertz signal in the channel to achieve high responsiveness. Additionally, the detector is equipped with a high-gain differential annular antenna and an integrated voltage amplifier, which can effectively amplify the mixing signals, thus improving the signal-to-noise ratio of the system, and ultimately enhancing the detector‘s responsiveness. The 1 × 3 detector linear array system composed of three pixels makes full use of the characteristics of the multi-layer structure of CMOS. The voltage amplifier is arranged below the antenna ground plane, which improves the utilization of the chip area and effectively reduces the production cost. The area of the detector system is 0.5 mm². When the gate is biased at 0.42 V, the measurement results show that, the maximum voltage responsiveness (Rv) can reach 43.8 kV /W under the radiation of 0.3 THz signal, and the corresponding minimum noise equivalent power (NEP) is 20.5 pW/Hz^1/2. The dynamic measurement results show that the detector can distinguish different material blocks.