The signal-noise ratio, dynamic range and sensitivity of long-wavelength (LW) infrared detector are limited by the charge capacity of digital readout integrated circuit (ROIC), which restricts the development and application of LW infrared imaging systems. The comparison and analysis of analog pixel and digital pixel ROIC technology were presented in this paper, the research status and main architectures of digital pixel focal plane array (FPA) were introduced. The 384×288 (25 µm) and 256×256 (30 µm) digital-pixel ROICs were designed with pulse frequency modulation scheme, and the designed comparator improved the power efficiency and robustness. Based on this, the digital LW FPA detector modules were designed with HgCdTe detector arrays, which measurement results were compared and analyzed with related works. The measured peak noise equivalent temperature difference are 3.4 mK and 1.9 mK, respectively, and the dynamic range achieves 96 dB. It’s confirmed that the digital pixel technology significantly improves the sensitivity and dynamic range of LW IRFPA, which manifests that this technology is a promising way to improve the performance of infrared detector.