Industrial decision-makers may wonder about the optimal timing for investing in carbon capture retrofitting in co-firing power plants, faced with uncertain benefits from upcoming China's carbon trading market and potential cost reductions derived from technology innovation. The decision on investment timing relates to the so-called waiting value, considering multiple uncertainties and trade-offs. This article applies a real options-based framework, adapted to deal with the waiting value in the context of multiple uncertainties of carbon market, technical improvements and biomass availability. The problem is solved through an efficient simulation method. The results suggest that the optimal retrofit timing for CCS (carbon capture and storage) in a co-firing CHP will be the year 2033 considering a basic scenario, in which the carbon price is 98 CNY/tonCO(2) (14.5 USS/tonCO(2)) in 2025, the growth rate and volatility are 5% and 7% respectively, and technical improvements are expected every six years and result in a cost reduction of 50%. In addition, we examine the effects of different sub-dimensions in the carbon market and technical improvement on anticipating the retrofit timing. The conclusions of this article provide decision-makers with strategies of adjusting the investment timing in response to their different expectations of market and technology developments. Further practical applications require judgments of future trends made by decision-makers and extensive data of specific cases.