The study involved estimating stem volume, calculating merchantable volume yielding rate and timber assortments volume with four parameter cylinder volume ratio stem profile. The result shows it performs better than Schumarher Hall at estimating stem volume when the data from Quercus aliena were classified by class. Compared with taper function at calculating merchantable volume yielding rate, four parameter cylinder volume ratio stem profile also performs well with systematic error below 1% and mean square error below 5%. To Pinus tabulaeformis trees, taper function has better accuracy degree than cylinder volume ratio method, but the result is contrary to Q.aliena. When calculating timber assortments volume with four parameter cylinder volume ratio method, systematic error is below 6% and mean square error below 19%.
