Nowadays, in modern manufacturing, the trend is the development of Computer Integrated Manufacturing (CIM). The productivity of CIM is highly depending on the scheduling of Flexible Manufacturing System (FMS). Shortening the makespan leads to decreasing machines idle time, which results in improvement in CIM productivity. This paper proposes a meta-heuristic approach called Ant Colony Optimisation (ACO) method for scheduling optimisation of FMSs by considering multiple objectives, i.e., minimising the idle time of the machine and minimising the total penalty cost for not meeting the due date concurrently. The results available for the various existing meta-heuristic methods (Jerald et al., 2005) are compared with results obtained by ACO method.