Abstract: Applying the theory of strain analysis and based on the data of the national A order and B order GPS network,the national astrogeodetic network has been checked.Through the strain analysis,the range and the feature of expanded and contracted deformation,wrest deformation and turn of the national astrogeodetic network have been shown clearly.According to the analysis result the authors pre-sent some suggestion for the choice of coordinate transformation model,and give a reasonable coordinate transformation model.