Information hiding technology is very important to wireless sensor network security, copyright protection and so on. This paper uses RSSI (Received Signal Strength Indication) as hidden information carrier and designs a Information Hiding Algorithm (RIHA). It does not affect original data or bring additional communication cost. RIHA is a novel information hiding method, which is very suitable for resource constrained wireless sensor networks. The simulation results show that RIHA has high hidden information transmission accuracy without bringing additional communication energy consumption. RIHA provides a new way for information hiding technology in wireless sensor networks.