Abstract: Abstract It needs methodology to study rectuirements evolution by quantitative methods. Based on ctueuing theory, this paper analyzed the process of requirements change rectuests and pointed out the characteristics of queuing models. The current method of calculating requirements maturity index was improved by M/M/1/m/m. An example shows that the quantities got from this ctueuing model have their meanings to evaluate the effectiveness of rectuirements analysis and the capability of requirements engineers. The funciton of queuing theory in guiding the management of requirements change was pointed out.

Key words: Requirements evolution, Requirements specification, Queuing theory