Mohamed,

Use context for this

Example

return {
    'type': 'ir.actions.act_window',
    'name': 'Name ',
    'view_mode': 'form', 
    'target': 'new',
    'res_model': 'Your.Model',
    'context': {'parent_obj': self.id} 
}

Inside the function of wizard object

@api.one    
def your_function(self):
     print self._context['parent_obj']

Thanks