Complementarity is an important attribute between different renewable energy sources (RESs). Multi-renewable energy system (MRES) offers an alternative to aggregate diverse RESs and make the best of their mutual characteristics. However, few papers conduct convincing research into the complementary operation of MRES. This paper investigates the complementarities in MRES that contains wind, photovoltaic, run -off hydro, pumped storage power plants and incorporates complementarity into optimal operation of MRES. The complementarity is theoretically summarized and firstly classified into natural and synthetical one. To effectively capture the uncertainty and complementarity of RESs, the time-dependent clustering simulation technique is employed to generate the joint-scenarios. An equivalent run-off hydropower plant index is proposed, based on which a novel complementary operation model that considers volatility and self-sufficient adequacy is established. Results are presented and compared in the case study, which demonstrate the validity and scalability of the proposed methodology, reveal the complementarities under multiple time-scales, and illustrate the significance of complementary operation.