The principle of lean mode is to create value for customers through value stream analysis. Firstly, this paper analyzes the characteristics of Value and Value Stream in R&D projects. Due to information stream is dominant in R&D projects, this paper proposes to use the index of Value of Work Performed (VWP) to weight the performance of projects. Then, using a R&D project as example and based on the Value Stream Mapping/Analysis (VSM/A), the monthly VWP and cumulated VWP are calculated. Finally, compared with Earned Value which results from Earned Value Management System (EVMS), the results indicate that VWP based on VSM/A can better reflect the implement performance of R&D projects. It makes up for deficiency of the application of EVMS in research projects.