春秋时期，晋公子重耳逃亡到国外，在途中饿晕了过去，介子推从自己的大腿上割下了一块肉，煮了一碗肉汤让公子喝了，重耳非常感动。 十九年后，重耳作了国君，封赏忘了介子推，很多人劝他讨赏，然而他去绵山隐居了。 晋文公听说后，亲自带人去请介子推，有人建议烧山逼出介子推。大火烧遍绵山，却没见介子推的身影，火熄后，人们才发现背着老母亲的介子推已坐在一棵老柳树下死了。为纪念介子推，晋文公下令将这一天定为寒食节。 第二年晋文公登山祭奠，发现老柳树死而复活。便赐老柳树为"清明柳"，并晓谕天下，把寒食节的后一天定为清明节。 The spring and Autumn period, Jin son fled abroad, in the way of hungry faint, Jiezitui push from own thigh cut off a piece of meat, a bowl of cooked meat soup to drink the son,Jin son was very moved After nineteen years, Jin sonbeaemperor, forgot to reward Jiezitui, many people advised him for the reward, but he went to live in seclusion at mianshan. After jinwengong hears, to bring people to please Jie, someone suggested that the mountain burned out jie. The fire burns mianshan, did not see the jiezitui push figure, after the fire was extinguished, it was found that carrying the old mother sitting in the meson pushed beneath an old willow tree is dead. To commemorate Jie, Jin ordered this day as the cold food festival. After climbing for second years, found that the death and resurrection of the old willow tree. Gave the old willow tree "Qingming Liu", and to the world, the cold food festival after the day as Tomb-sweeping Day. 本文来源：https://www.wddqw.com/doc/f112ee120622192e453610661ed9ad51f01d546b.html