Abstract: In recent years, there has been widespread attention given to the effects of urbanization on extreme climate changes. This paper investigates the urbanization effects on local extreme climate in Urumqi, the largest city in Xinjiang, Northwest China, based on 22 indices of climate extremes which calculated from observations from 1961 to 2018. The results show that urbanization has a significant impact on the frequency, intensity, and duration of extreme climate events. The urbanization has negative effect on the change of extreme warm indices, while showing a positive effect on the change of extreme cold indices and extreme precipitation indices. Besides, urbanization has delayed the abrupt change of cold events and led to a cluster period of extreme precipitation in urban. The extreme cold (warm) indices are significantly negatively (positively) correlated with major urbanization factors. Furthermore, urbanization will continue to affect the region's climate extremes in the future, and may make the local climate even more extreme. Urumqi exhibits a unique urbanization climate effect due to its arid zone climate background.