Benefit from the caching hits on the routers along the request routing path, in-network caching plays an important role in diminishing the distance between the consumers and their desired contents. A content caching model is proposed to intuitively analyze the small world characteristics of in-network caching in information centric networks. A directed long edge from a caching node to the provider of its stored content is created with the probability of the content replica's cache hit ratio. Simulation results validate that the information-centric networks demonstrate the small world characteristics due to the adoption of in-network caching.