WSN generates large and different type of data. Hadoop is introduced to handle such type of data. Hadoop is a framework which can easily handle different type of data and process very fast using HDFS and Map Reduce respectively. In WSN there are number of sensors nodes, each sensor node collects data and delivers to cluster head and cluster head delivers data to the Base station. Base station which transfers data to HDFS for storing, HDFS easily stores data and process it using Map-reduce. In-between Base Station and HDFS there is no security mechanism. To overcome this problem we use trust based model, through which Name Node of HDFS verify that Base Station is genuine or not. This will enhance the security of the whole mechanism and make the system secured.