Abstract: Wireless sensor is the biggest researching area. Now days most of the applications are working on wireless medium. In wireless sensor network Injecting invalid data attack is very serious threat. If invalid data is stored in sink than due to error decision waste of energy and bandwidth will take place. In this paper presenting a new scheme for wireless sensor network which is help in power optimization and efficient bandwidth consumption base on message authentication code (MAC). This Scheme theoretical and results are helping in the WSN application areas and improves the performance and accuracy through draining the injected invalid data.