Wireless sensor network (WSN) is composed of large number of sensor nodes with Limited computation power, storage and communication capabilities. The wireless communication employed by sensor network facilitates eavesdropping and packet injection by an adversary. The Security of the wireless sensor networks depends on the existence of strong and efficient key distribution mechanisms.The main task is to safely distribute the shared keys to the sensor nodes with high connectivity, good resilience with minimum resource requirement. The solution to key distribution is such that, a pool of symmetric keys is chosen and a subset of the pool (key chain) is distributed to each sensor node. Two nodes that want to communicate search their key chain to determine whether they share a common key; if they don't share key in common then there may be a path, called key path, among these two nodes where each pair of neighboring nodes on this path have a key in common. In this paper we have shown a novel key pre distribution algorithm based on number theory which uses Chinese Reminder Theorem.