Mid-wavelength infrared （MWIR） imaging technology plays a crucial role in aerospace， medical diagnostics， and autonomous driving. Van der Waals material black phosphorus （BP） exhibits exceptionally high carrier mobility and an ideal direct bandgap， making it a proven candidate for high-performance room-temperature MWIR sensing. However， the stringent growth conditions and anisotropic growth characteristics restrict the development of BP optoelectronic devices to small-scale laboratory demonstrations. Therefore， there is an urgent need to develop large-scale， uniform， and high-performance BP photodetector arrays. This study employed a room temperature preparation technique to deposit a large-area， uniform， low-oxidation BP ink film onto thin-film transistors， resulting in the development of a 64 × 64 high-performance MWIR snapshot photodetector array. The room temperature ink preparation process effectively prevents the oxidation of BP during fabrication， achieving an oxidation loss as low as 1.12%. In addition， a gradient centrifugation strategy was employed to optimize the lateral size and thickness distribution of the nanosheets in the BP ink， thereby facilitating the transport of charge carriers. The BP ink film array demonstrated a high photoresponsivity of 4.52 mA/W in the MWIR range， with pixel light response non-uniformity as low as 10.1%. This study presents a new approach for advancing large-scale MWIR imaging technology.