This paper addresses a single-machine bi-criterion scheduling problem where the jobs fall into several classes. A sequence-independent setup time is required when the process is switched from one class of jobs to another. The objective of this paper is to find an optimal schedule that minimizes the total completion time subject to a constraint that each job must finish before its deadline. An exact solution incorporating with a number of properties and a lower bound are proposed to tackle this problem, and the efficiency of the proposed procedure is then tested by computational experiments.