I am connecting my Android device to PC, but its not show my internal storage.
Is there a method to access the internal storage of Android while connecting the android device to PC.
You could use ADB for this. In connection with graphical frontends like e.g. QtADB this makes it easy to access your device's storage. Access from the command line is also possible (see the linked tag-wiki).
Another possibility is to install a SSH server on your device, which you then could access using either an ssh command line client, or also with graphical applications like e.g. WinSCP.
How much of your internal storage you can access either way depends on whether your Android device is rooted. Only portions of the internal storage are accessible for users other than root.