The utility model discloses a high pressure fan with a certain cubage of eccentric rotating impeller type that is characterized in that: an air inlet and an air outlet are respectively arranged on the right and left position on the outer central line of a shell; a principal shaft is arranged on an upper eccentric bearing seat on the vertical central line of a front and back shell covers at the two ends of the shell; an impeller lower shaft is arranged on an impeller bracket that is arranged on the principal shaft; a free turning plate and a bearing are arranged on an inner bearing bracket of the front and back shell covers; a bearing wheel on the upper part of the impeller is arranged inside a groove of the free turning plate. The machine driving the free turning plate to act synchronously through the eccentric force and friction of the impeller and absorbs air from the right side; when the impeller turns from point a to point b and presses the air in area B to area C for discharging and takes the air in area A to the area B so as to finish the circulation work. Compared with the previous technique, the utility model has the advantages of an easy structure, convenient maintenance, save raw material, low electricity consumption and wide application; thus the utility model discloses a product for replacing the prior fan.