Abstract: The active/passive imaging system has two imaging modes, with high integration, low cost, high system operation efficiency and good application prospect. A 64×64 multifunctional infrared focal plane array (FPA) readout integrated circuit (ROIC) was presented. Under the limitation of 30 μm pixel center distance, four imaging functions had been realized on this ROIC: Daylight standard imaging, low light level imaging, asynchronous laser pulse detection and two-dimensional laser ranging. Based on the TSMC 0.35 μm process, the chip design, tape out and test verification of multifunctional ROIC were completed. The layout area was significantly reduced by using circuit reuse design and pixel sharing architecture. The T-switch of CTIA was adopted to effectively reduce the leakage current and to improve the dynamic range of infrared passive imaging circuit, which made the dynamic range up to 60 dB in high gain mode and 68 dB in low gain mode. And the well capacity reached 203 ke⁻ in high gain mode and 1.63 Me⁻ in low gain mode. Three-stage push-pull amplifier and MOS feedback resistor made RTIA have both high gain and small layout area. The test results show that the circuit has active/passive imaging functions and good performances. It can be applied to infrared FPA lidar imaging system.