There are many different beliefs about the origin of the Lantern Festival. But one thing for sure is that it had something to do with religious worship.
One legend tells us that it was a time to worship Taiyi, the God of Heaven in ancient times. The belief was that the God of Heaven controlled the destiny of the human world. He had sixteen dragons at his beck and call and he decided when to inflict drought, storms, famine or pestilence upon human beings. Beginning with Qinshihuang, the first emperor to unite the country, all subsequent emperors ordered splendid ceremonies each year. The emperor would ask Taiyi to bring favorable weather and good health to him and his people. Emperor Wudi of the Han Dynasty directed special attention to this event. In 104 BC, he proclaimed it one of the most important celebrations and the ceremony would last throughout the night.
一个传说告诉我们,这是一个礼拜的时间太乙,在古时候天上的神。他们相信上帝的天堂,控制了人类世界的命运。他有十六龙听他使唤他决定何时造成干旱,风暴,饥馑和瘟疫降临人间。与秦始皇开始,第一个皇帝团结的国家,后来皇帝下令所有灿烂的仪式,每年。皇帝想请太乙带来风调雨顺和良好的健康,他和他的人。无棣的汉代针对特别关注这一事件。公元前104年,他宣布了它的一个最重要的庆祝活动和仪式将持续整个晚上。
参考资料:http://zhidao.baidu.com/question/367847979.html