can python scripts be used instead of vbscript in QTP, if so, please put some light on this.
Short answer: no, it looks like it's VBScript only.
Long answer: Assuming you mean HP QuickTest Professional, its summary on Wikipedia only lists VBScript as a supported scripting language, and the current Microfocus UFT website (the new name for the product, it appears) mentions that it's scriptable but doesn't indicate the language.
This Github gist in Python demonstrates you could run UFT tests by starting them off with Python, but that's not the same as being to script the tool itself in Python.