In this study the filtration velocity and filtration pressure drop at the beginning of bag cleaning were used as experimental parameters to evaluate the bag-cleaning performance of a pulse-jet baghouse. The effective residual pressure loss was used to indicate the cleaning performance after bag cleaning. Two different test dusts, fly ash and limestone, were used. The critical cleaning indices under different operation conditions for bag cleaning were also investigated. A critical average pulse overpressure was found to exist beyond which bag-cleaning performance did not improve much. It was found the filter＇s final filtration resistance is an important parameter to decide whether a Venturi is necessary for a good bag-cleaning performance or not. Use of a Venturi was found to increase the average pulse overpressure for a system with a filter＇s final resistance coefficient greater than about 500 Pa.s/cm. However, no Venturi is recommended when the filter＇s final resistance coefficient is smaller than 500 Pa.s/cm.