The present invention relates to a method for preventing gas mingled contamination in air chamber of fuel cell. The content of the invention relates to a method for preventing gas mingled contamination in at least one air chamber of fuel cell (1) in the stopping period of fuel cell (1). The method comprises the following steps through generating excessive pressure in at least one air chamber: forming an educt which is conveyed to the fuel cell at an operating mode for operating the fuel cell (1) at a state of energy inputting; conveying the educt for filling the air chamber thereby filling the air chamber by educt partially at least; and filling the air chamber thereby generating excessive pressure in the air chamber and basically preventing the gas mingled contamination.