Intake pipe design is important for rotary engine performance due to great influence on in-cylinder flow and combustion characteristics. This paper analyzes the effect of intake pipe deflection angle on the performance of a gasoline rotary engine. In the parametric study, the intake pipe is deflected from the left to the right with a 10 deg interval and the maximum deflection range of 30 deg at each side. A computational fluid dynamics numerical simulation model of the rotary engine is established. The simulation results show that when the intake pipe is deflected to the left from the original design, the engine volumetric efficiency first increases and then decreases with an increasing deflection angle. During ignition, the turbulent kinetic energies in the cylinder increase with an increasing deflection angle. When the intake pipe is deflected to the left by 30 deg, the turbulent kinetic energy is increased by 85.9% compared to the original design. The peak cylinder pressures first increase and then decrease with an increasing deflection angle. When the intake pipe is deflected by 10 deg to the left, the peak cylinder pressure is 9.3% higher than that of the original design. The maximum NOx emission can be increased by 4.8% and the minimum NOx emission can be decreased by 13.3%. It is found that deflecting the intake pipe to the left enhances the tumble effect and increases the combustion velocity. Overall, deflecting the intake pipe to the right is less effective than deflecting to the left. This analysis provides a comprehensive understanding on intake pipe design for rotary engines.