High technology industries have stringent on clean room environment. Traditional ballroom type clean room can¡¦t meet the requirement in many cases. The uni-directional laminar ballroom type cleanroom is can¡¦t fulfill such requirement. The adoption of Mini-Environment technology is becoming the mainstream of the environment control technology for high technology industries process. It is the goal of this project to simulate and design the air flow pattern, in using the current injection machine as a model, to achieve the cleanliness of class 1,000 ¡V 10,000. There are four major steps in achieving this goal, Namely: 1¡BThe dynamic 3D CFD simulation of the flow pattern of the clean bench. 2¡BThe evaluation of the pollution source and its impact on the overall cleanliness 3¡BThe basic design of the class 1,000 cleanroom for this machine 4¡BThe modification necessary to achieve this goal through design iterations. The results of this research are useful in the understanding of the flow characteristics in a mini-environment. The buffer zone of laminar flow was found to be effective to avoid cross contamination with the outside environment during door opening. The height of the processing opening of the mini-environment is found to be an important factor on the flow turbulent intensity and particle concentration. Concentration due to an operator can also be reduced by this buffer zone. The numerical techniques developed can also be used as numerical models in future studied.