I want to know if ordinary Indian passport holders are eligible for VOA at Hainan ?

Ram, in principle Hainan VOA should be available to most citizenship of the world, but in reality Hainan VOA is something that Chinese authorities are trying and succeeding in slightly eliminating at least at the time being. They are giving absolute advantage to Hainan 30 day free visa access, but unfortunately, Indian citizens are not eligible for this option. I would say, to be on the safe side, you should obtain pre-arranged Chinese visa. Simply speaking, don't risk with Hainan VOA.

Hope they make it clear without ambiguity on the list of nationalities that are eligible for VOA.