The headwater regions of the Tarim River Basin (TRB), Asia's vital "water towers," are critical for the ecological stability of arid Northwest China, yet a systematic understanding of their diverse precipitation microphysics remains elusive. This study addresses this gap by analyzing a decade (2014-2023) of Global Precipitation Measurement/Dual-frequency Precipitation Radar observations, complemented by ERA5 reanalysis, across the TRB's eight major headwater systems. Our analysis reveals a fundamental north-south dichotomy in precipitation regimes, driven by contrasting environmental controls. The northern headwaters (Tianshan slopes), influenced by mid-latitude westerlies, are characterized by a moisture-rich and dynamically active environment. This fosters deep continental convection featuring efficient collision-breakup cycles (large , high ) and stratiform rain with effective ice-phase growth. Conversely, the southern headwaters (Kunlun slopes), adjacent to the Taklimakan Desert, exhibit a distinct microphysical signature. Here, shallower convection produces a "small-, extremely high-" raindrop distribution, consistent with aerosol-inhibited raindrop growth, while stratiform rain is governed by the melting and subsequent breakup of large snow aggregates. These findings demonstrate that regional variations in moisture supply, large-scale dynamics, and background environment are the primary modulators of microphysical pathways. This work provides a crucial observational benchmark for improving quantitative precipitation estimation and refining climate model parameterizations in this ecologically sensitive region.