In this paper we develop the confidence intervals for estimating the expected value of the units in the system and the maximum likelihood estimates of the parameters are derived for truncated singlechannel Markovian queue with balking, reneging and reflecting barrier by using quality control process under steady -state simulation. Some important queueing systems are developed and discussed as special cases of the model. A simulated numerical example is used to illustrate its application for estimating the parameters under quality control process.