Abstract: A novel elliptical arc rotor was developed to solve the cusp problem of rotor profile of existing twin-crew vacuum pump.First,the elliptic meshing model was mathematically formulated.Next,the profile equations were derived and solved,and the rotor profile was constructed with the calculated elliptic arc and its envelope; besides,the pair of rotor with the newly-developed profile was simulated with Solidworks software.The simulated results show that the rotor pair meshed quite well.Finally,the influence of the variables,such as the central angle of the tooth back,on the construction of the elliptical arc profile was investigated for design optimization.As shown in the calculation of the characteristics,the novel elliptical arc rotor outperforms the existing arc-corrected rotor because of a larger area utilization ratio,a shorter space contact line and a smaller leakage triangle.