用on。

例句：

1. 全世界的华人在阴历一月十五号都会庆祝元宵节。Lantern Festival is celebrated on the fifteenth day of the first lunar month every year by Chinese people around the world.2.常在阴历年的第一个月的第十五天庆祝。It is celebrated on the fifteenth day of the first month of the lunar year.