The photovoltaic HgCdTe detectors with capacitive transimpedance amplifiers (CTIA) readout circuit is irradiated by various in-band lasers. All is found that the nonirradiated detection units′ basal signals have responded, when the incident laser power density increases about to 10-2 W/cm2. The responded value initially decreases and then increases, and the noise increases with the power density increasing. With further investigation, it is demonstrated that the paradoxical responded phenomenon is primarily caused by the public P pole structure of linear array detectors and the public Vref voltage structure of circuits.