Provided is a digital cable system and method for protecting a secure micro (SM) client, and more particularly, a digital cable system and method for protecting an SM program that can improve the security of an SM program through authentication of a host and integrity verification of the SM program. A method of protecting an SM program includes: receiving host authentication information associated with a host from a trusted authority; verifying validity of the secure micro program based on the host authentication information; and sending, to an authentication proxy, a HostStateInformation message that includes host state information associated with validity verification information of the SM program.