A research proposal is not a letter of motivation, or a personal statement. It should describe a potential research project you might like to carry out.
In the research plan we would like to read about your ideas for doing research under the supervision of the professor you would like to work with. In writing a research plan, we want you to demonstrate that you are sufficiently familiar with a subject area to develop scientifically sound ideas for doing research. Please keep in mind that your proposal has to fit into the professor's research interests. Your research plan should not exceed 5 pages in length. It is not necessary to submit the research plan to the professor for approval first. You should send it directly to Beijing Office together with the other application documents.