Embodiments of the present disclosure provide a method and apparatus for security assurance of a network function or service. The method comprises: generating security requirements for a network function based on a security profile and a deployment and runtime environment of the network function; generating a security policy and a security test specification for the network function based on the security requirements; deploying the network function based on the security policy; validating security compliance of the network function with the security test specification; and activating the network function or service, in response to the network function being in compliance with the security policy.