Decorated disiocations in olivine from the upper mantle xenoliths have been examined with a scanning electron microscope (SEM) using a backscattered electron image (BEI). Experimental results indicate that dislocation patterns and grain boundaries are a clear bright image and easily observable. The resolution of this method for dislocation observation is about an order of magnitude better than that of optical microscopic observation. The method of dislocation using a backscattered electron image is especially useful in the study of high dislocation density and dense dislocation boundary in naturally and experimentally deformed olivine and in the determination of quantitative parameters of microstructures.