The key technology of the constant pressure and constant current cam plunger pump used in the in vitro diagnostic analyzer is the trajectory curve formed by the cam. According to the trajectory of the plunger, the trajectory curve of the cam was calculated and simulated in SolidWorks software. It was found that there was a deviation between the cam trajectory curve and the ideal trajectory curve, so the constant pressure and constant current performance of the cam plunger pump was affected. In order to optimize the cam trajectory curve, Catmull-Rom cubic interpolation curve was used to fit discrete points and NURBS flexible curve was used to control vertex position and weight factor. The cam curves obtained by the two methods were compared with the ideal trajectory curve. The results show that the cam trajectory curve obtained by the latter is closer to the ideal trajectory curve. In order to verify the calculated results, a testing platform for cam plunger pump was built, and the flow pulsation was measured by using a foreign advanced micro flowmeters. The experimental platform can feedback the change of flow rate in realtime, and the different data before and after optimization are reflected in the form of curve. After testing, the flow fluctuation and fluctuation rate after optimization are obviously smaller than those before optimization, which meets the needs of in vitro diagnostic analyzer.