In recent years，people are concerned more about social trust and family happiness. However，there is no study on the relationship between social trust and family happiness. Based on China Family Happiness Survey in 2014，the relationship is investigated. It is found that firstly，the variables such as age，marriage status and self-reported health level have significant effect on social trust；secondly，it exists a significant positive relationship between trusting others and being trusted by others；thirdly，social trust follows a hierarchical order and people tend to trust institutional units such as government and policemen；lastly，people have higher family happiness scores when they have higher social trust level or they are trusted more by others. This study will improve peoples’ understanding on social trust problems in China and inspire people to improve peoples’family happiness scores and family construction from increasing social trust level.