Abstract: A reputation model of sensor nodes in WSNs named AEMP was proposed. AEMP means 'Addition Encoura gement, Multiplication Punishment'. Compared with current other models, AEMP can work with simple calculation and need fewer resources. So it is fit for the character that sensor nodes in WSNs have limited resources. Emulation experiments show the model can depress the reputation value of the node that executes bad communication behaviors quickly.And it can also reduce the possibility of wrong judgment. The mode affords a new routing algorithm for designing a WSNs routing protocol.

Key words: Wireless sensor networks, Reputation evaluation, Security routing protocol