Integrated energy system (IES) coupled with renewable energy generation and power-to-gas (P2G) technology provides an effective solution to alleviate the current urgent carbon peak demand. Therefore, This paper develops a novel IES low-carbon economic operation strategy incorporating market mechanism. Firstly, a 24-h joint wind turbine and photovoltaic (WT-PV) output scenario generation method is proposed based on the time-varying Copula function. Secondly, the introduction of carbon capture technology (CCT), electrolyzer (EL), methane reactor (MR) and hydrogen fuel cell (HFC) refines the operation process of p2g into two stages. The combined heat and power (CHP) and HFC variable power operation strategy with adjustable thermoelectric ratio is proposed. Finally, the ladder-type carbon trading mechanism is used to guide IES to control carbon emission. The results of case study show that 1) The time-varying Copula function is effective in improving the scenario accuracy and fitting the data closely to reality 2) The introduction of hydrogen improves the energy utilization efficiency while promoting the consumption of WT-PV. 3) The variable power operation reduces the total cost and carbon emission by 2.4 % and 3.14 %, respectively, compared with the constant thermoelectric ratio. 4) The proposed IES operates reliably and economically under reasonable carbon trading parameters.