Wireless sensor networks are characterized by multi hop wireless lossy links and resource constrained nodes. Energy efficiency is a major concern in such networks. Due to their constraints in computation, memory, and power resources, the performance optimization is a challenging task in these networks. In this paper, fuzzy based secure data aggregation technique is used to select the secure and non-faulty node members for data aggregation. The aggregated data from the cluster heads is transmitted to the sink. This technique efficiently checks for malicious nodes based on the system parameters and maintains a secure aggregation process in the network. By simulation results, we show that our technique has improved throughput and packet delivery ratio with reduced packet drop and less energy consumption based on rate.