The purpose of SCD file check method introduced in this paper is to check whether the SCD file details have been changed and to manage SCD file version. SCD file check method is based on mathematical principle of set, function, mapping and variable comparison. First, each component, element and data attribute are respectively abstracted into set, function and variable in this method. Row number and column number are used respectively to count the number of elements and the number of data attributes. Then, sets, functions and variables can be assigned by two-dimension positioning, which uses the actual values of uniquely identified data attributes as the assignments of variables to be checked. Finally, the check result of SCD file is obtained by checking these assignments. The uniqueness of these variables to be checked is ensured by the one of object identifier Ref. In this way, SCD file check method can reliably check the difference of SCD file details, to the accuracy of version number, value of data attribute, virtual terminal number and external/internal signal description. The check method and procedure in this paper provides technical measures for review, revise and management of SCD file, and avoids the error changing of SCD file effectively.