There could be a few reasons for this.

1 Lack of water

will cause stress and the flowers will dry up and drop off. Deep watering is best.


2 Lack of pollination

Normally the flower is wind pollinated, if the weather has been very wet, humid or very hot this will cause the flower to either become very sticky and not be able to fall and pollinate. If too hot you can get inactive pollen, the plant doesn't think it can support any more fruit so it won't pollinate.

You can hand pollinate - take a small, clean paintbrush and move this around the inside of the eggplant flower.

You can fertilize with a fish emulsion. I've also read about people using Epsom Salts. Dilute with water and water the plant. This can also help the flowers hold on more until they are pollinated.

Cut off any excess leaves.

Hope these suggestions help.