Gridded precipitation，potential evapotranspiration（PET），and land surface temperature（LST）data‐ sets provide valuable alternatives for hydrologic modeling in ungauged areas. However，their performance in specific regions requires further investigation. This study evaluates six gridded precipitation products（CHIRPS， CMORPH，GPM，GSMaP，MSWEP，and PERSIANN），three PET products（GLDAS，GLEAM，and ERA5- Land），and one LST product（MOD11A1）in the Taolai River Basin. The effects of different precipitation and PET inputs on actual evapotranspiration（AET）and soil moisture were also analyzed. The results indicate that runoff simulations vary significantly depending on the precipitation product used. GPM and MSWEP perform best，achieving Nash-Sutcliffe efficiency（NSE）values of 0. 58 and 0. 54，respectively，during the validation period. These two products are reliable alternatives for precipitation sources in data-scarce scenarios. In contrast， the selection of PET products exhibits limited impact on runoff simulations，with the NSE values ranging from 0. 61 to 0. 74. If runoff simulation accuracy is the primary concern，the GLDAS，GLEAM，and ERA5-Land products are suitable substitutes. Additionally，when surface temperature data are unavailable，the MOD11A1 product achieves an NSE of 0. 61 during the validation period. For scenarios with no meteorological observations，combining GPM or MSWEP precipitation data with any of the three PET products and MOD11A1 yields NSE values exceeding 0. 53 in both calibration and validation periods. This study confirms that gridded datasets can partially mitigate hydrological simulation challenges in data-scarce regions，while recommending expanded applicability assessments across more basins to enhance reliability.