The electromagnetic environment adaptation test is an important reference for equipment operation application. In view of the requirements of the electromagnetic environment adaptation test and evaluation for radar countermeasure equipment， this paper untangles the test environment’s requirement based on the typical operation mission of the equipment， proposes the basic method for constructing the electromagnetic environment in the test， establishes the adaptation evaluation index system， and analyzes the effects of the electromagnetic environment on the signal intercept probability， reconnaissance range， and sorting and identification. In the calculation of the influence of the electromagnetic environment on the reconnaissance range of radar countermeasure equipment， the energy of jamming signals is considered as reconnaissance’s noise， and the distance formula in free space is used to derive the reconnaissance range formula under jamming， which is then verified by simulation. The results show that the significant decrease of reconnaissance range is associated with the alignment between reconnaissance antenna and interference source. Integrating the operation influence of the different complexity of electromagnetic environment with adaptation status， this paper proposes a method for electromagnetic environment adaptation evaluation and shows the feasibility of the method by an example.