Abstract: The utilization of energy storage as a high-quality frequency modulation resource can effectively address the power deviation in the system caused by the uncertainty of wind power output. Under the electricity market framework, the wind-storage system can yield profits in the energy market and frequency modulation auxiliary service market through joint bidding. The bidding strategy of the wind farms and energy storage power stations jointly participating in the market is investigated under uncertain scenarios in this paper. Firstly, the operation mechanism of wind-storage system participating in the energy and frequency modulation auxiliary service market is introduced, followed by proposing a coordinated bidding framework and analyzing the income. The Monte-Carlo method and scenario reduction techniques are employed to tackle the uncertain scenarios. On this basis, a joint bidding model is developed with the objective of maximizing the wind-storage system profit. Finally, case studies are conducted using operation data from a wind farm with energy storage, thereby validating the ability of our method in improving the economic benefits of both wind farms and energy storage stations.