Abstract: The successful detection method of skeleton types of diterpene alkaloids from Spiraea japonica var using the difference of collision energy of electrospray ionization tandem mass spectrometry(ESI-MS 2) was described in great detail. By the analysis of MS fragmentations of 9 diterpene alkaloids from Spiraea japonica var, it indicated that under the optimized instrumental conditions, hetisine-type diterpene alkaloids were more stable than atisine-type alkaloids. The collision energy for the secondary dissociation of atisine-type diterpene alkaloids was obviously lower than that for hetisine-type ones. So the difference of collision energy in electrospray MS 2 can be used as evidence to identify the structural types of diterpene alkaloids isolated from Spiraea japonica simply and rapidly. The report of this identification method is the first found in domestic references.