Abstract: At the beginning of the British leasing WeiHaiWei, the territory is peaceful, only the demarcation in 1900 leads to sino-foreign conflict. The conflict is unclear, and it is necessary to study. In the spring of 1900, in front of the demarcation, there were lots of rumors circulated among the people, saying that Britain would impose higher tax and poison the natives. So, the natives assembled together to resist tax and demarcation. The British thought rumor coming from the gentry. So they dispersed the rallies and told them the truth, but there was little effect. Chinese officials brought wrong information, which spread the rumors further. In the process of the joint demarcation, people gathered to block. Chinese officials proposed to suspend, but the British determined to continue, which caused the people to carry out violent protests. Under the repression of the Chinese Regiment, nearly 30 people were killed. Then the British officials completed the demarcation unilaterally. The starting point of the natives violence was to to resist tax disposition, and the reason was their believing of rumors. The main responsibility of the conflict lies in the officials of Chinese and British, and the biggest victim is the natives.