The invention discloses a handheld formaldehyde testing device. One end of a first pressing sheet is elastically hinged to one end of a hand holding plate through a first torsional spring. A second pressing sheet and the first pressing sheet are elastically hinged to the hand holding plate through a second torsional spring symmetrically at an interval. A detection region is arranged between the first pressing sheet and the second pressing sheet. Cutting saw teeth are arranged on one lateral side, in the detection region, of the hand holding plate. A slidable storage drawer is arranged on the other end face, symmetrical to the face where the first pressing sheet is located, of the hand holding plate, and can slide in the length direction vertical to the hand holding plate. A handle is arranged on one side, close to the cutting saw teeth, of the storage drawer, and a paper discharge outlet is arranged on the other symmetrical side of the storage drawer. One end of formaldehyde test paper is reeled in the storage drawer, and the other end of the formaldehyde test paper penetrates out through the paper discharge outlet and is pressed to the hand holding plate through the first pressing sheet and the second pressing sheet. The handheld formaldehyde testing device can acquire accurate detection results on site efficiently and rapidly, and is convenient to operate.