This paper deals with the design and stress analysis of spur gear of GT-1 Power Tiller (Global Tiller-1). It is widely used in Myanmar because they are more efficient and cheaper than any others types of tractors for agricultural works. The fundamental dimensions of engine are four strokes with compression ratio of 22.5. It produces maximum rated output power of 15 hp at 2400 rpm and maximum speed 24.2 km/hr at 2400 rpm. In gear design, gear material is chosen Carbon Steel (AISI 5160 OQT 400) and all gear are the same material. The gears are designed to transmit power and satisfy the dynamic check. In gear design, the number of teeth, face width, gear tooth features and pitch diameter are calculated. Three-dimensional model of Spur gear is drawn by using SolidWorks Software and analysed by Finite element method. The spur gears are designed according to the point of view of the strength. The result of spur gear design and stress depend upon the tooth profile and gear material properties. The spur gear is analysed with Carbon Steel (AISI 5160 OQT 400). Boundary constraints are defined and the deflection and strain for three-dimensional model are analysed.