The invention discloses a multi-energy complementary grid-connected system applied to electrified railways and a control method. The multi-energy complementary grid-connected system is bridged betweena power supply arm of a traction transformer [alpha] and a power supply arm of a traction transformer [beta], and mainly comprises a wind power generation portion, a photovoltaic power generation portion, an energy storage portion, a comprehensive energy control portion, a DC support capacitor, a single-phase transformer and a single-phase back-to-back converter. Coordinated control for four power generation configurations of the multi-energy complementary system is accomplished based on traction load, wind and optical power prediction data; smooth scheduling is performed on unstable electricenergy through real-time data detection and processing so as to ensure the power supply reliability; and power supply mode selection is performed according to real-time traction operating conditionsso as to realize reasonable consumption of renewable energy sources. Meanwhile, active power transfer is realized through controlling the single-phase back-to-back converter, and corresponding reactive power and low-order harmonic current are outputted dynamically, thereby playing a role of reducing or eliminating negative-sequence current at a primary side of the traction transformer and complementing the reactive power and harmonic waves.