Motion sickness(MS) has long been a difficult medical problem in aviation, space flight and navigation. It has become an important direction of research about how to test the efficacy of anti-motion sickness medicine(AMSM) quickly and accurately. The paper presents a fusion model by Dempster-Shafer evidence theory (DSET) for pharmacodynamic estimation of AMSM. Establishing diagnostic decision-making frame is Θ={effective treatment, ineffective treatment, uncertain of treatment}. The decision-making parameters are divided into the nystagmus parameters and blood microcirculation parameters according to the category. Fusion result contrasts with the Graybiel score. We found that fusion results is more obvious. It shows that fusion system has higher determination, and less subjectivity influence which is disturbed by outside factors. The mathematic model can manifest the MS symptom of the quizzee. The model can acquire important reference information for further study in the pharmacodynamic estimation of AMSM.