Portable folding wheelchair

A portable folding wheelchair comprising a seat frame and a backrest, wherein the seat frame includes a front U-shaped tube and a rear U-shaped tube coupling with each other in a middle section on two sides through a pin to form a X-shape from sideward, the front U-shaped tube and the rear U-shaped tube having respectively an upward opening, the rear U-shaped tube having a lower end on two sides to couple with a rear wheel, the front U-shaped tube having an upper end on two sides to fasten to a connection plate, the connection plate connecting to the backrest, the front U-shaped tube having a lower section on two sides to pivotally engage with an upright tube, the upright tube having a lower end coupling with a front wheel, the upright tube and the rear U-shaped tube having an upper end bridging a sleeve, the sleeve having a front end forming a notch, the upright tube having an upper end pivotally engaging with the notch through a pin, the sleeve further having an opening formed on a lower section in the longitudinal direction to allow the sleeve to couple with the upper end of the rear U-shaped tube, the sleeve having two lateral sides on a middle section to form respectively a slot to couple with a bolt to engage with the rear U-shaped tube, the sleeve further having a flap extending outwards from an outer side on a rear section thereof, the rear U-shaped tube having a retaining pin corresponding to the flap, the upper ends of the two upright tubes being bridged by a front stretcher, the two connection plates being bridged by a rear stretcher, the front stretcher and the rear stretcher being coupled with a seat canvas.