Tomb-sweeping Day is a chinese traditional festival. It is between the middle and late spring, 108days after Dongzhi (mid winter). At that day, people sweep the tomb, remember those who have died.
The origin of this festival starts at Chunqiu period. （770 b.c.~403 b.c. ) Jin(country)'s noble son, Chong Er, is in exile to escape from persecution. He is starving and dehidrating. His accompany, Jie Zitui, cut off one piece of meat form his leg and make a bowl of meat soup to feed Chong Er. Chong Er soon recovered. When he finds out where the meat comes from, his eyes is covered with grateful tears.
19 years later, Chong Er becomes the monarch. He treat the accompanies who helped him when he is exile well, but forget Jie Zitui. Jie Zitui distains those people asking for reward, so he didn't ask for anything, packed up and went back to Mianshan mountain with his old mother.
When Chong Er finds out he forget about Jie Zitui, he feels ashamed and wants Jie Zitui back. But the mountain is high and has dense vegetation, so he accept the advise to light up 3 sides of the mountain, hope Jie Zitui will escape from the other side. But Jie Zitui never come out. He was found dead under an old willow with his old mother. Chong Er is very compunctious, regreting for what he did. He found tracks written with blood in the tree hole: "cut my leg and serve the meat to show my loyalty, hope you will always be Qing Ming(clear and bright)"
Later, Chong Er set the day Jie Zitui died as Qing Ming festival.

相传春秋时期，晋公子重耳为逃避迫害而流亡国外，流亡途中，在一处渺无人烟的地方，又累又饿，再也无力站起来。随臣找了半天也找不到一点吃的，正在大家万分焦急的时候，随臣介子推走到僻静处，从自己大腿上割下了一块肉，煮了一碗肉汤让公子喝了，重耳渐渐恢复了精神，当重耳发现肉是介子推自己腿割下的时候，流下了眼泪。

十九年后，重耳做了国君，也就是历史上的晋文公。即位后文公重重赏了当初伴随他流亡的功臣，唯独忘了介子推。很多人为介子推鸣不平，劝他面君讨赏，然而介子推最鄙视那些争功讨赏的人。他打好行装，同悄悄的到绵山隐居去了。
晋文公听说后，羞愧莫及，亲自带人去请介子推 ，然而介子推已离家去了绵山。绵山山高路险，树木茂密，找寻两个人谈何容易，有人献计，从三面火烧绵山，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。晋文公见状，恸哭。装殓时，从树洞里发现一血书，上写道：“割肉奉君尽丹心，但愿主公常清明。”为纪念介子推，晋文公下令将这一天定为寒食节。
第二年晋文公率众臣登山祭奠，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。