Abstract: A GC method for examinating rosin was presented. The different contents of isopimaric acid in rosins of Pinus massoniana and P.elliottii, which are 15% respectively, can be utilized to judge whether a rosin is a blended one. A P. massoniana rosin is judged to be blended with some P. elliottii rosin when its content of isopimaric acid is > 2%.