By using indicators of self-citation rate (CsR) and knowledge flow rate (FR), and combining citation networks from both citing and cited perspectives, it is revealed that the discipline with the lowest CsR and FR is statistics, which indicates that statistics plays an important role in the knowledge output. Among the 23 CSSCI disciplines, 11 are inflow ones and the remaining 12 are outflow ones. Economics and management are two major disciplines in which knowledge keeps frequently inflow and outflow.