Abstract: A language named CPEBSDL (communication protocol entity behavioral specification and description language) is presented. The CPEBSDL language has a powerful ability on protocol description, it can describe protocol entity's states, behaviors and controlling and accessing to resources. The CPEBSDL regards the interaction between protocol entities as entities' control of the same resource. So the interactions between protocol entities can be denoted by the resources that entities mutually control. When a complicated protocol is required to describe by CPEBSDL, every single protocol entity's description can be established respectively, and then the whole description of protocols can be obtained by integrating every single protocol entity's description. In this point, the CPEBSDL make protocol analysis and testing easier. The CPEBSDL' regulation is proved to be equal to a context-free grammar G(CPEBSDL) and the G(CPEBSDL)is transformed to its Chomsky normal form. Based on those foundation, an algorithm that can validate whether a given protocol behavior sequence accords with CPEBSDL' regulation is proposed. Compared with traditional and classical protocol description languages, the CPEBSDL can decompose complicated protocol's behaviors to every single protocol entity's behaviors. Furthermore, the CPEBSDL can be easily translated into Petri nets, in which protocol's Petri nets can be modeled automatically if the protocol is described by the CPEBSDL. For example, the whole procedures of describing LAPD protocol using CPEBSDL are given and an example of validating the protocol behavior sequence is given too.