The invention relates to a boiler, in particular to a high-capacity fuel gas condensing hot water boiler adopting compound water circulation. The purpose is to solve the problems that because carbon steel helical finned tubes of the hot water boiler are corroded seriously, condensation is not thorough, and heat efficiency of the boiler is low. Two partition plates in the boiler are arranged in an upper boiler drum and a lower boiler drum respectively, and an air preheater is communicated with a rear water cooling wall of the hot water boiler through an economizer; the economizer is a steel-aluminum composite finned tube type economizer, the air preheater is a steel-aluminum composite finned tube type heat pipe air preheater, finned tubes of the economizer and the air preheater are respectively formed by carbon steel base tubes, outer aluminum-coated tubes and aluminum fins, the carbon steel base tubes are coated with the outer aluminum-coated tubes, and the aluminum fins are arranged on the outer walls of the outer aluminum-coated tubes; forced circulation is adopted for a high-temperature heated surface, so that water speed is ensured, safety of the water circulation is improved, and vibration possibly induced by stagnation, backflow and subcooled boiling is avoided; natural water circulation is adopted for a low-temperature heated surface, so that power consumption is reduced, and a power outage protection function is achieved. The high-capacity fuel gas condensing hot water boiler is used for heat supply.