Abstract: Workshop scheduling is studied based on painting workshop of complex flexible production in the bus assembly enterprise. A scheduling model based on constraint rules is provided by discussing relationship between job process time span and unit occupying time span. The model is implemented by IBM ILog Cplex software. Tests prove that under spare production capacity conditions, the model can process massive production data on workshop scheduling in a short time, including flexible processing technology and flexible product path, re-entrant job and flexible working and rest time to satisfy product release time and delivery time, shorten the production cycle, effectively reduce the workshop finished product inventory and optimize scheduling plan of workshop.