Communication and modern information technologies have created many changes in the recent societies and have influenced different parts of social life too. Based on the existing statistics, most use of the Internet belongs to the youth who use the Internet for their scientific and research aims. Studies on the effects of using the Internet by young people can help identify some outcomes of this technology. For this reason, the authors tried to investigate the effect of Internet upon the social capital of the youth. In this research, Information collected by using survey method and multi-stage cluster sampling of 390 of the youth from the city of Ghaemshahr. The results showed average social capital (trust and social networks) among Internet users, higher than non-users and hence Internet plays a complementary role of social capital. The results showed that there was a significant negative relationship between income and the amount of social capital. Also, the family income was the most effective (negative) in the explanation of social capital. Among all the variables in the path analysis model, the variable of family income had maximum effect (positive) on social capital.