Abstract: A portable electronic tree-diameter dendrometeris was developed based on a strain sensor to automatically measure and recordthe diameter of a tree. The main hardwares constituting the device were micro-electro-mechanical systems, sensor, tape and reel.Through A/D, the pulse count of the sensor was converted to the perimeter and diameter of the tree, which would be embedded in the operating software, to realize the digitization and accuracy of tree-diameter measurement. Beyond the existing product design ideas based on optical principles and mechanical principles, this study developed a new approach of integration, miniaturization, digital development of dendrometer.