In wireless sensor networks, all communications between any two sensor nodes occur in a shared and open wireless medium, which makes it easy for an adversary to eavesdrop on every message transmitted. While message encryption can protect the content exchanged between the nodes, routing information may reveal the identities of the communicating nodes and their relationships. For this purpose, the existing schemes used an onion packet, random walk, or storage migration to provide anonymity. These schemes incur high computation cost and communications cost. In this paper, we present a lightweight anonymous routing scheme to provide anonymous communications. In contrast to the existing schemes, we first use a Bloom filter to hide the identities of the sensor nodes, and thereafter, generate per-hop pseudo-link identifiers to accomplish routing and data packets forwarding tasks. This scheme not only conceals the node and the link identities in the data packets, but also helps to achieve traffic anonymity due to content analysis. In this paper, we describe not only the mechanisms to efficiently establish source routes and forward data packets anonymously, but also provide its proof of correctness.