Abstract: In order to scientifically guide the design of the bag filter project by theoretical derivation and engineering verification, for the first time the widely used non-woven fiber filter cloth bag filter dust collection efficiency formula: η=1-exp■. On this basis, analysis and research on several commonly used different filter materials and structures that combined with a large number of engineering practices, Therefore, a practical and simplified dust removal efficiency formula has been derived: η=1-exp■. Engineering application results show that this formula is feasible in the design of bag dust removal projects in different industries such as coal-fired boilers and cement kilns, and can ensure that the outlet dust concentration reaches to 10 mg/m~3, or even 5 mg/m~3 of ultra-low emission or under various design requirements such as special emission limits, the error between the actual filter area of the project and the design filter area is within ±0.6%.