Abstract: In developing hydraulic computation applications on Compaq Visual Fortran(CVF), only to call Win32 API functions cannot meet all the needs of its functionality extension, and thus the paper arises a problem to be solved how to create Win32 DLL made up of C/C++ functions by VC in accordance with Fortran users, in order to extend CVF API. A thorough discussion is carriedout, in which how to call conventions of VC and CVF and how to coordinate between them are given, alphabet string, multidimension array and derived type in combination with Fortran 90 are correspondingly set up in C/C++ functions, etc.. And at last, some and typical examples are presented.As a result, a developing guideline is provided for VC creating Win32 DLL suitable for CVF.