The present invention relates to communication technologies and discloses a method and an apparatus for protecting security of data, so as to solve the problem of the prior art in which the security of data transmission between a communication terminal which has a characteristic of small data transmission and the network cannot be guaranteed. Information relevant to security context is stored if a communication terminal has a characteristic of small data transmission; current security context is obtained according to the information relevant to security context; and security protection of communication data is performed by employing the current security context. The embodiments of the present invention may be applied to a communication system having a characteristic of small data transmission, such as an MTC and the like.