In this paper, multipurpose scheduling and design problems are treated simultaneously in order to minimize investment cost of plant with taking into account completion times, cycle times and equipment sizes. Usually, equipment sizes are considered as continuous variable. And processing time of task is usually assumed to be independent of batch size. However, most of manufactured equipments have their standard volume. And processing times are dependent on batch sizes. In this research, the volumes of equipments are considered as discrete variables and processing time is a function of batch size in order to apply these optimization problems to real industries.