According to the gridded Chinese ground precipitation dataset with a resolution of 0.5°* 0.5° released by National Meteorological Information Center, extreme precipitation indices including maximum 1-day precipitation (RX1day), maximum 5-day precipitation (RX5day), very wet day precipitation (R95), wet day precipitation (PRCPTOT), consecutive dry days (CDD) and simple daily intensity index (SDII) in arid areas in Northwest China during 1961-2011 is analyzed using Sen's slope, correlation analysis and other methods. The connection between each extreme precipitation index and the Arctic oscillation is discussed, and the gridded indices in this study are compared with those in previous research using observation data. The result indicates that most indices show a slightly increasing trend, except CDD with statistically significant decrease (P<0.01). Spatially, RX1day, RX5day, R95, PRCPTOT and SDII have significantly increased in the western part and slightly decreased in the east part, and CDD generally presents a decreasing trend. The higher correlation (P<0.05) exists between NCAR-based summer Arctic oscillations index and CDD, which indicates a relation between Arctic oscillation in summer and drought events in the study area. Compared with the previous research using observation data, the gridded data have greater spatial coverage, which is good at describing detailed spatial variation, especially in the mountainous regions like the Tianshan Mountains and Altai Mountains.