The influence of social and cultural factors on family financial decision making has gradually attracted the attention of the academic field, and social trust is the core element. This paper makes an empirical study on urban families, using the data of Chinese Family Panel Studies(CFPS), and the result shows that: as the social trust increases, the possibility of urban households risk asset market participation and the ratio of risk assets will significantly improve; Different kinds of social trust have different influences on turban family financial risk investment decision, for instance, the government trust and common trust can promote the increasing of risk investment, but the neighborhoods trust can have an opposite influence; For those households that have not received financial education, the improvement of their social trust level has a more significant impact on financial risk assets investment decisions.