Hi, I am a Myanmar passport holder

You do not need any kind of visa because you will be covered by 24 hour visa free transit. I advise you to print out your flight tickets and to have the printouts at hand, ready to be presented to relevant authorities.

If you want, you can even apply for a temporary entry permit upon your landing in Haikou if you want to explore the city or to have a rest in the hotel. If you intend to do that, you will approach, immediately upon your landing in Haikou, to transfer counter where you will apply for a temporary entry permit. Please, have in mind that the granting of the permit is not a passenger's right, but more like a bonus during your layover. In other words, your chances to be granted a permit are good because of the length of your layover, but not guaranteed. The detail that is guaranteed is that you can travel via China absolutely visa free.