There is an ongoing debate on the attributes of trademarks that only be used as keywords of search engine promotion, namely trademark infringement, unfair competition or legitimate use. There are many different judgments in judicial practice. This paper begins from the theory and practice of trademark use in keyword promotion, and argues that the behavior that trademarks are used only as keywords does not belong to trademark use in trademark law, and it is not easy to confuse the public. Although trademark use as keyword promotion does not constitute trademark infringement in trademark law, it may be adjusted by anti-unfair competition law if it is achieved by unfair means and clearly violates the principle of honesty and credit and the generally recognized business ethics. Otherwise, the law should not intervene and leave the market to choose. We should prevent improperly expanding the application of anti-unfair competition to hinder the free competition, and carry out the legal policy of promoting innovation and encouraging free competition.