Abstract: PURPOSE The purpose of this study was to investigate the mechanical property of lingual and labial archwires by using finite element method. METHODS A three-dimensional finite element model including three maxillary left incisors of the 0.022-inch Dentaurum Discovery labial and Ormco 7th Generation lingual brackets was constructed and threaded with corresponding labial and lingual archwires. Then the arch wire’s mechanical property in different materials, sizes and space between brackets were analyzed. RESULTS The load deflection curve of lingual archwire was similar to labial archwire at the same distance of brackets and mainly determined by the characters of archwire. The effects of the type of wire alloy were greater than dimension but less than the coordination of the two: the load value of lingual archwire increased when archwire size increased (the load value of 0.019 × 0.025 inch stainless steel wire was about 1.46 times as bigger as 0.017 × 0.025 inch one),but this change was less than the material of archwire brought(the load value of stainless steel was about 2.73 times as bigger as the same size of titanium-nickel wire),and was less than the coordination of the two(the load value of 0.019 × 0.025 inch stainless steel wire was about 3.5 times as bigger as 0.017 × 0.025 inch titanium-nickel wire),the force of the lingual side was larger than the labial side at the same conditions, when the distance of brackets increased ,both of them decreased gradually(the force loading on 10 mm, 12 mm and 14 mm was about 2.42, 1.59 and 1.33 times as bigger as on 16 mm , respectively), faster in the early, later became stabilized.CONCLUSIONS Lingual archwire should be in smaller diameter, lower stiffness than labial archwire. In choosing arch wire clinically, the material of arch wire should be considered first, followed by size and coordination of the two, meanwhile the distance of brackets should also be considered.