The features of ZigBee make it suitable for the application of data acquisition system. A method which is designed for the ZigBee-based data acquisition system is proposed. Most traditional positioning based on ZigBee uses wireless signal loss model to locate. The work is affected by the impact of the surrounding environment. If we take experience value in reality and sets it as parameters in the model, both the positioning accuracy and the universal of this method are not in ideal. With Curve Fitting method fitting the relationship between RSSI and distance, then RSSI triangle centroid algorithm is used to calculate the coordinates of the nodes to be measured. Actual experimental result shows that the algorithm can improve the positioning accuracy.