In machine cutting, the replacement of traditionalKGcutting solution with cryogenical cold air jet not only possesses a good cooling and lubricating efficiency, but also can avoid the occurrenceof environmental pollution.

This paper advances the functions of Bernoulli Equation in judging the direction of air flow after laneway perforation, analyzes the establishment of mathematical method of Bernoulli Equation, expounds the determination of airflow mechanical energy before laneway perforation, and elaborates the determination and requirements of concrete parameters of mechanical energy.