Forest resources inventory includes individual tree DBH（diameter at breast height）, individual tree height, individual tree volume, stand average DBH, stand average height, stand density and stand volume. The theoretical basis was based upon the principle of photogrammetry, image-processing technology and forest measurement, and the forest intelligent dendrometer was developed which was composed of the self-developed R&D PDA module, EDM module and rotational station. There were four modular procedures which were compiled in the Java language and developed in Android Studio 2.1 systems development environment, and five measuring functions, such as tree height, DBH, three-element volume calculation, 3D angle gauge plot and basic measurement, and they were implemented by getting dip angle, azimuth, distance, image information and other parameters. Validated by experiments, the measuring accuracy of tree height was as high as 97.13%, DBH was 97.08%, volume was 94.52%, stand average height was 98.09%, stand average DBH was 98.05%, stand density was 96.59%, and stand volume measurement accuracy was 95.72%. Thus the equipment was in line with the accuracy requirement of national forest inventory (NFI), which can be promoted to be used in the forestry inventory.