Question
sir, we have orange garden. these days some oranges in orange crop r turning orange in colour earlier than their normal time and falling down from trees.
sir, one more thing their is a very little hole in oranges which fell down also .
so please suggest me what should i do.

Answer
Vishal:
You may have an insect infestation based on your description.  Correct ID is necessary to customize a management strategy.  You are probably not going to be able to ID the insect from the hole it makes in the orange.  Suggest opening a few fruit and looking for the immature insect. Contact your local garden center or nursery to get an ID form that immature that you find. Put it in a small container of alcohol to preserve.

You may wish to search "Google images" on the computer internet for orange borers to try for a photo match.
Regards
Steve