Abstract: Nowadays，two-stage vacuum extruder has been widely used in brick and tile industry，and main direction in the future of extruder research is to squeeze out high density，high mechanical strength，moderate moisture content and uniformity，good surface quality′s adobe.Elastic-visco plastic model of mud was established through the study of rheology and fluid mechanics.Constitutive equation of brick and tile mud was built through studying the relationship of stress- strain-time.Effect factors of rheological properties of mud were analyzed concretely.Main factors that affecting quality of extrusion were found through analysis and research of extruder structure and actual working process.Feasible control scheme was put forward.