A high-speed imaging readout circuit for a linear-mode HgCdTe APD was proposed. A resistive feedback transimpedance amplifier (RTIA) with adjustable transimpedance gain was used in the image element to realize the real-time linear conversion of the photocurrent, and the phase margin of the RTIA was optimized using the capacitive compensation method to solve the output oscillation phenomenon at low gain. The results showed that the RTIA transimpedance gain within the image element was 100~140 dB, the GBW could be improved by 10¹⁴ times, and the output delay of the image circuit was lower than 1.6 ns. A column-level time-of-flight measurement circuit and a two-stage time-to-digital converter were used for the wide-area coarse quantization of the time-of-flight and high-precision fine quantization, respectively. The measurement range was up to 1 530 m, with a measurement accuracy of 106.5 cm and a linearity of greater than 99.99%.