Abstract: Brain-computer interface（BCI）is able to convert human brain signals into computer commands by collecting, analyzing and processing electrical signals in human brain, realizing information exchange and control between the human brain and external devices. It has important application prospects in the fields of medicine, education, entertainment, military, etc. It has entered the stage of clinical application, and is about to be put into large-scale industrialized application. BCI technology, through the direct interaction between the system and human brain, assists, enhances and changes human brain’s conscious activities, which will fundamentally change the natural person’s expression of meaning and formation of meaning, while the boundaries of the Civil Code’s protection of natural person autonomy of intentions are still limited to several situations where external forces lead to freedom of meaning. Civil law should recognize the validity of the user’s expression of meaning expressed through the machine form of BCI technology of “brain to machine”, and if the expression is inaccurate due to systematic reason, the expression of meaning is still valid, but the right of revocation should be given to the expressive person. BCI technology of “machine to brain” has substantial influence and intervention on the formation of the meaning of natural person, but should also be treated as the meaning of natural person. The subject of liability in the application of BCI technology is the user rather than the AI or the system itself; therefore, the user should bear the responsibility for breach of contract, quasi-contractual liability and tort liability. The current civil law theories and rules have explanatory power and applicability to the current issues related to the application of BCI technology, but new issues in the field of civil law brought about by brain-computer interface technology should be considered.