i am working was python script developer,i want to write certification exam(certified professional) in python,can you name such cetifcation exams?
There aren't really any Python certifications at this time, at least not ones which anyone would have any reason to pay attention to; Brainbench has one, as does ExpertRatings, but I doubt that any company would really make hiring decisions based on them (while some companies do ask you to take those tests, they don't appear to require them). The only one which could be considered in any way 'official' would be the one from O'Reilly and Associates, which hasn't been released yet (it is slated to be out next month). Even that is more a certification that you took their coursework (at considerable expense), rather than a demonstration of proficiency.
As for writing a certification exam, as opposed to taking an existing exam, well, you're on your own with that.