This paper posits that urbanization reshapes individuals' risk preference by exerting self-selection and assimilation effects. Taking advantage of the unique Hukou system in China, we innovate a quasi-experiment method to elicit the two effects, employing the 2013 wave dataset of the Chinese General Social Survey (CGSS). We find strong evidence supporting our two-effect theory, and the magnitudes of both effects are sizable and similar in scale. The assimilation effect reduces the migrant's risk