var
  aIP, aSubMask, aDns, aGateWay, ipcmd, dnscmd: string;
  ini: TIniFile;
begin
  try
    ini := TIniFile.Create(ExtractFilePath(Paramstr(0)) + 'Ipconfig.cfg');
    aIP := ini.ReadString('Main', 'ip', '');
    aSubMask := ini.ReadString('Main', 'SubMask', '');
    aDns := Ini.ReadString('Main', 'Dns', '');
    aGateWay := ini.ReadString('Main', 'gateway', '');
    ipcmd := 'netsh interface ip set address name="本地连接"   source=static addr="' +
      aIP + '"  mask="' + aSubMask + '" gateway="' + aGateWay + '"  gwmetric=1';
    winexec(PAnsiChar(AnsiString(ipcmd)), sw_hide); //调用cmd命令设IP  }
    Sleep(1000);
    dnscmd := 'netsh interface ip set dns name="本地连接" source=static addr="' + aDns
      + '" register=PRIMARY';
    winexec(PAnsiChar(AnsiString(dnscmd)), sw_hide);
    Sleep(1000);
    WinExec(PChar(Paramstr(1)), sw_show);
  finally
    FreeAndNil(ini);
  end;
end;

IPconfig.cfg

[Main]
ip=192.168.66.166
subMask=255.255.255.0
gateway=192.168.66.1
Dns=202.96.128.86
[TaiZi]
ip=192.168.10.221
subMask=255.255.255.0
gateway=192.168.10.1
Dns=202.96.128.86