Abstract: Based on the double tail fin and fixed wing UAV, the structure model of the fuselage was designed by using the SolidWorks. In order to optimize the design of small UAV fuselage and reduce the body mass and air resistance for better application in the forest fire prevention, we used ANSYS-FLUENT to simulate the fuselage. The grid structure was generated by ICEM CFD ANSYS mesh generator to generate the PRISM mesh. The fuselage aerodynamic analysis was carried out. By FLUENT software simulation, we improved the design, and analyzed the difference of the fluid field, resistance and weight before and after improvement. Results showed that the optimization of fuselage aerodynamic shape had significant effect in reducing drag. The air resistance of improved fuselage was decreased by 45.9%, and the fuselage quality was reduced by 27.8%. Our research adds a new chapter in the field of fuselage optimization, and provides guidance for aerodynamic optimization.