Use a plastic material that can hold boiling water (good heat conduction)? Turn the hat upside down, preferably in the air? Put hot water in it? Just play 10 for a few minutes. Remember not to put it away immediately after recovery? It's best to put it out of reach, okay? Just leave it overnight.

Blow a balloon to support the hat, hold some newspaper balls under the brim according to the desired arc, and dry them. If the hair dryer is not ideal, just blow it casually, and be careful not to burn it.

Hot steaming method: whether you bring a lot of hot steam into the bathroom or put hot water in the basin under the hat in a narrow space, wrap it in plastic bags to soften the grass of the straw hat, then knead it into the size of the inner ring of the straw hat with newspaper, then knead it into a certain shape according to the shape of the straw hat, and then let the hat stand in the shade. After a while, the grass dries and the hat takes shape.