ABSTRACTThe purpose of this work is to optimize the blade design of an axial-flow fan.Four different chord length and five twisting angle of their blades were studied. Thefan was designed by using NACA 5505 series. The first investigation is conducted tothe blade design in the variation of chord length. The base chord length is constant of130 mm and the tip is vary from 84, 92, 102 and 110 mm. The second study is in thevariation of twisting angle from 0, 10, 20, 30 and 40o. The performances of the fanswere measured in a Von Mises stress criterion under pressure of 500 Pa. From thevariation of chord length, the shortest length of 84 mm was delivered the loweststress. While the variation of twisting angle, the lowest stress is delivered by 40o oftwisting angle. The proposed blade design is presented by using combination oftwisting angle 10, 20, 30 and 40o in single blade model. The blade total length of446.5 mm is divided into four parts and every part have different twisting angle.From the stress result, the proposed model was delivered lower stress compared to theother models.Keywords: Axial fan, twist angle, chord length, stress analysis, finite elementmethod.