The present invention relates to an extrusion die and a method for extruding a sheet using the same, and according to one aspect of the present invention, there is provided an extrusion die comprising a storage part configured to hold a raw material, the storage part defining a first width, a pressure part configured to move the raw material through the storage part, a first die defining a second width less than the first width, such that a flow width of the raw material becomes narrower, a second die in fluid communication with the first die, the second die defining a width that increases from the second width to a third width, such that the flow width of the raw material passing through the first die becomes wider and a flow thickness becomes smaller, and a heating part configured to heat the raw material passing through the second die.