Labels are the foundation for implementing multilevel systems and the prerequisite of enforcing mandatory access control in secure systems. How to define and enforce label functions which support multiple security policies is the focus here. A security label common framework (SLCF) based on static object label and dynamic subject label is put forward. SLCF introduces the notation of access history and provides a complete label funtions set. Based on SLCF, both multilevel confidential policy and multilevel integrity policy can be expressed and enforced. SLCF is implemented in a secure operating system based on Linux, the experimental results show that the system based on SLCF is flexible and practicable.