Abstract: The test data visualization is very useful to study the train aerodynamics. In this paper, a new data interpolation method that combines a data field quadrilateral grid and region transformation based on the isoparametric transformation is proposed, because the data field of train aerodynamics test is the scattered data field based on curved surface. And the scanning algorithm is improved to overcome the defect of traditional algorithm, whose convergence is not ensured. In order to be able to expand the test data visualization system, the object-oriented approach is applied to the program. Finally, the test data visualization system is realized and tested, then the program is improved in practice.