Generally speaking, you should submit your application in person and collect your passport with an issued visa. If circumstances really prevent you from doing so(e.g. illness), you may entrust someone else to do it for you (no need to provide a power of attorney) providing that you have prepared all the documents required and signed the application form.However, citizen of other countries are required by the Chinese Embassy and Consulate-General to submit the applications person to the Visa Centre.