#include <ShlObj.h>

 BOOL SimulateDropFile(CString strFilePath)

 {

     char szFile[MAX_PATH] = {};

     wcstombs(szFile, strFilePath.GetBuffer(), _MAX_PATH);

     DWORD dwBufSize = sizeof(DROPFILES) + strlen(szFile) + ;

     //通过类名或窗口标题 找到接受拖拽的窗口

     HWND hMain = ::FindWindow(NULL, _T("XX播放器"));

     if (hMain == NULL)

         return FALSE;

     BYTE* pBuf = new BYTE[dwBufSize];

     if (pBuf == NULL)

         return FALSE;

     BOOL bResult = FALSE;

     memset(pBuf, , dwBufSize);

     DROPFILES* pDrop = (DROPFILES*)pBuf;

     pDrop->pFiles = sizeof(DROPFILES);

     strcpy((char*)(pBuf + sizeof(DROPFILES)), szFile);

     DWORD dwProcessId = ;

     GetWindowThreadProcessId(hMain, &dwProcessId);

     if (dwProcessId != NULL)

     {

         HANDLE hProcess = OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_WRITE, FALSE, dwProcessId);

         if (hProcess != NULL)

         {

             LPSTR pszRemote = (LPSTR)VirtualAllocEx(hProcess, NULL, dwBufSize, MEM_COMMIT, PAGE_READWRITE);

             if (pszRemote && WriteProcessMemory(hProcess, pszRemote, pBuf, dwBufSize, ))

             {

                 ::SendMessage(hMain, WM_DROPFILES, (WPARAM)pszRemote, NULL);

                 bResult = TRUE;

             }

         }

     }

     if (pBuf)

     {

         delete[] pBuf;

         pBuf = NULL;

     }

     return bResult;

 }

在调用该函数之前，先打开接受拖拽的进程
ShellExecute(NULL, L"open", exe完整路径, NULL, NULL, SW_SHOWNORMAL);