本文提出了两种罗茨泵圆弧转子型线：其一，转子峰形为圆弧，谷形为其共轭曲 线；其二，转子谷形为圆弧，而其峰形为它的共轭曲线。文中分析了两叶、三叶和四叶 罗茨泵转子情况，提供了转子啮合的几何关系式：给出了转子理论型线和实际型线的解析方程式；推算出容积利用系数的关系式；并通过电算给出了 λ＝ｆ（Ｒｍ／Ｒ）的关系表 及参数选择范围。 In this paper, two types of roots rotor pump arc rotors are proposed: one is that the rotor peak is arc and the valley is its conjugate curve; the other is that the rotor valley is arc and its peak shape is its total Yoke curve. In this paper, the rotor conditions of two-lobe, three-lobe and four-lobe Roots pumps are analyzed and the geometric relation of the rotor meshing is provided. The analytical equations of the theoretical profile and the actual profile of the rotor are given. The relational formula of volumetric utilization factor is deduced. And by calculating the relationship between λ = f (Rm / R) and the parameter selection range.