What is the concept of kowtow in Christianity? I am a Chinese.
In China, every year on Ching Ming Festival, Chinese people go to the tombs of their dead ancestors to kowtow.
Christianity prohibits kowtow to ancestors, which means disrespect for ancestors in the Chinese concept.
During the Qing Dynasty, many missionaries came to China to preach, but very few Chinese believed in Christianity. Their attempt to turn China into a Christian country failed.
What do you think of this matter?
What is the concept of kowtow in Christianity?
According to the Wikipedia article partially quoted below, the Chinese tradition of bowing low three to nine times before the tomb of their ancestors is a mark of respect:

The Kowtowing ritual in front of the grave is performed in the order of patriarchal seniority within the family. After the ancestor worship at the grave site, the whole family or the whole clan feast on the food and drink they have brought for the worship either at the site or in nearby gardens in the memorial park, signifying the family's reunion with its ancestors. Source: Qingming Festival (Wikipedia)

There are various cultures that use bowing to living persons as a mark of respect.  For example, Japanese businessmen will demonstrate the degree of respect being given depending on how low they bow, or how slightly they bow.  The tradition of ‘kowtow’ to a living person is nowhere prohibited within Christianity.  Indeed, the Bible has many instances of where a person would even prostrate themselves on the ground before a mighty ruler, or when in the presence of deity.  Neither is the cleaning of gravesites prohibited within Christianity.
What the Christian Bible forbids is praying to dead ancestors.
In some cultures ancestors are believed to influence the lives of later generations by blessing or cursing them; in essence, acting as gods. So praying to them, presenting them with gifts, and making offerings are done to appease them and gain their favour.  This is where showing respect morphs into worship and since Christians are told to worship only the Creator God of the universe, in whose image we are made, then it would be wrong for a Christian to engage in such things.
The Bible tells us in Exodus 20:3-6 that we are not to worship any god other than the Lord God Almighty.  Furthermore, since diviners and sorcerers were thought to be able to contact the dead, they were also expressly forbidden by God (Exodus 22:18; Leviticus 19:32, 20:6, 27; Deuteronomy 18:10-11; 1 Samuel 28:3; Jeremiah 27:9-10).
The belief that spirits continue to reside on earth after death and influence the lives of others is not Christian.  The Bible shows that the dead are unable to influence the living.  They can no more bless or curse than they can breathe.  The dead know nothing at all.  They do not deserve any form of worship, and that includes praying to them.  We are to pray to God, through Christ Jesus.  He is the only mediator between God and men.
You say that during the Qing Dynasty, many missionaries came to China to preach, but very few Chinese believed in Christianity. Their attempt to turn China into a Christian country failed.  Then you ask What do you think of this matter?
I think the fact that Christians in China are persecuted and forbidden by the Government to worship in freedom is testimony to the fact that those early missionaries did not fail.  It also speaks volumes about the people who wish to suppress freedom of religion.  What are they afraid of?