Comparative hydrology is a new concept in hydrological study. The author indroduces contemporary international development of the study. On the basis of a review of the problems in caparative hydrology, the present paper deals with the scope of research work, including principles, objectives and analytical approaches. The author states that China is one of largest counties in the World with a considerable variety of hydrological types which are favourable to research on comparative hydrology. Finally, a research proposel is presented for Chinese geographical/engineering hydrologists: 1. Establishment of an entire system for various hydrological types; 2. Enhancement of the study of hydrological processes for all hydrological types; 3. Development of a data bank and information system for comparative hydrology; 4. Development of comparative hydrology models for transferring hydrological predications from one area to another.