Security has become an important aspect for Web Service technology. Along with the deep research of security technologies, a set of measureable and quantifiable indexes for evaluating security quality are strongly required. As a new research topic of Web Services security, Quality of Protection (QoP for short), which provides several security levels of security mechanisms for different components or users, can meet the security requirements in the service composition or in service selection scenarios. This paper gives an overview of QoP, provides the definition and evaluation indexes of QoP and implementation mechanisms of Quality of Protection in Web Service research area, and discuss some further topics for future research.