Assembly line optimisation is an important process. When the system is complex, mathematical modelling and design of experiments becomes difficult. Hence process simulation approach is adopted here. Contribution of this research is improvement of performance of assembly line by maximising the measurement of performances like cycle time, throughput, resource utilisation and also by reducing cost. Key features of this research are development of eight different models for different input variables without disturbing existing set up. This what-if analysis is done using Arena process simulation software. Effect of layout, resource distribution, combination of operations, time study, Maynard operation sequencing techniques (MOST) has been studied here. Combinational effect of all these parameters are difficult to analyse analytically, hence unique simulation approach is selected. MOST is useful to find value added and non-value added activities. Lean techniques like kaizen, total productive maintenance, line balancing, low cost automation are used for different scenarios.