According to a sensor network system and a method for processing sensor data, a sink node collects sensor data from sensor nodes, performs a prediction algorithm which is the same as a prediction algorithm performed in the sensor node to obtain a prediction value, when a sensing value is received from the sensor node, updates the prediction value to the sensing value, stores the sensing value as sensor data, determines whether the sensor node is a representative node when the sensing value is not received from the sensor node, and stores the prediction value as sensor data if the sensor node is the representative node, and corrects the prediction value based on the sensing value of a representative node and stores the corrected prediction value as sensor data if the sensor node is not the representative node.