The invention relates to the technical field of gas turbines, in particular to a gas turbine rim sealing structure. The structure comprises a static vane connected to a static vane platform and a movable vane connected to a movable vane platform, wherein an airtight cool air channel is formed between the static vane platform and the movable vane platform, blowing holes are formed in the peripheral direction of the static vane platform and communicated with a static vane cooling channel, an outlet of each blow hole is located on the downstream side of the static vane platform and communicated with the airtight cool air channel, and the blow holes are used for guiding cooling air in the cooling channel out and making cooling air form an air curtain at the position of an outlet of the airtight cool air channel. The invention further relates to a rim sealing method. By the adoption of the method, cooling air in the static vane cooling channel can be guided out from the downstream side of the static vane platform, and the air curtain can be formed by cooling air at the position of the outlet of the airtight cool air channel. The air curtain can improve the airtight performance of the gas turbine rim sealing structure, reduce airtight cool air amount, reduce the influence of airtight cool air on aerodynamic efficiency of main current, and improve overall efficiency.