Object To apply microwave technique to the extraction of free anthraquinones from Rheum emodi Wall. and the methods of microwave extraction and traditional extraction were comparied. Methods The orthogonal test design was used to arrange sequent experiments to test the effect of the three main factors including microwave power, particle size of herb and extraction time on the extraction efficiency of free anthraquinones and to establish optimal extraction process. A parallel test was carried out using the three different methods including the optimal extraction process, the traditional decocting method and the alcohol refluxing method. Results Particle size of herb and microwave power are the significant factors with P