A design method of roots pump rotor profile based on NURBS curve was proposed. Combining the design process from peak curve to valley curve, the reasonable design area of peak curve was designed, and the envelope condition of NURBS curve was solved. The method of determining the rotor profile of roots pump with NURBS curve by control point and weight factor was designed. The method redesigned the involute rotor profile and the average error was in 0.1 μm which was in a reasonable error range. The feasibility of designing Roots pump rotor profile with NURBS curve was verified. Finally, the involute rotor profile was improved and optimized by using the local adjustable characteristic of NURBS curve. The area utilization factor of the rotor profile was increased by 1%. This provides a theory and method for the design of the rotor profile of Roots pump.