The method of sea surface partial pressure of CO₂ (pCO₂) timeseries studies is simply summarized, and the advances in indentifying pCO₂controlling processes, revealing interannual variability in pCO₂, monitoring the influence of some climatic events on pCO₂, and estimating airsea CO2 fluxes based on timeseries studies are reviewed in detail. Generally, pCO₂ time-series studies are conducted by ship-based investigation and autonomous buoy CO₂ measurement. Besides some qualitative observation of irregular and episodic events that influence pCO₂, timeseries study could quantitively calculate separate contribution of various controlling processes to pCO₂ variation, which is of importance for revealing pCO₂ controlling mechanisms. Moreover, time-series studies on interannual time-scales show that human activities have caused the increase of sea surface pCO₂. As well, El Nio and La Nina events could significantly influence sea surface pCO₂ and air-sea CO₂ fluxes. In addition, it is crucial to conduct time-series studies for improving the estimation of air-sea CO₂ fluxes.