Abstract: Establishing a pair-wise key between nodes is important to secure communications in wireless sensor networks. Because traditional solutions for key management are difficult to implement in a resource-constrained environment, several methods, such as key pre-distribution, have been proposed to achieve the goals of data secrecy and integrity. In this paper, a new key management scheme KMVTR based on variable transmission range of sensor nodes is proposed. This scheme uses group-based deployment method and pre-distributes keys in groups and between groups. In each group, there are certain special nodes which can assist nodes from adjacent groups in establishing a pair-wise key. The KMVTR scheme can use the powerful senior nodes act as such special nodes, and can also use normal nodes act as such special nodes. The theory analysis and simulation result shows that the connect probability of two adjacent groups will be high enough when using normal nodes act as special nodes. The analysis also shows the communication energy cost of the KMVTT scheme is acceptable for wireless sensor networks. Compared with other methods, the KMVTR scheme has several advantages such as providing perfect resilience against node capture, supporting larger network size, and doesn't have to know the expected locations of sensor nodes in key pre-distributed phase.