Abstract: Aiming at the phenomenon of small world of knowledge flowing on informal knowledge networks,using the method of MAS,building a knowledge flowing model based on the classic WS small world model,we studies the occurrence mechanism of the phenomenon.The results show that the exponential decay of relation strength is necessary for the phenomenon,the efficiency of knowledge flowing in the networks is seriously sensitive to the distribution of relation strength and the mean value of relation strength on networks will influence the evolutionary speed but notinfluence the evolutionary pattern.

Key words: informal knowledge networks, relation strength, small world of knowledge flowing, exponential decay