The invention discloses a wind and light complementary power generation and power supply system based on output of a three-port direct-current converter. The three-port direct-current converter comprises a first input port, a second input port and an output port; a Buck converter is embedded into a positive polarity output converter, the second input port is an input port of the positive polarityoutput converter, the first input port is an input port of the Buck converter, and the output port is connected to a direct-current load and an inverter or is used for external power supply through adirect-current bus; a wind power supply and a photovoltaic power supply can be controlled for external electric power supply simultaneously or external electric power supply independently by controlling the working conditions of three switch tubes; the quantity of used devices is reduced, the cost of the power supply system is reduced, and the power supply efficiency and work reliability are improved.