With the computational fluid dynamics software FLUENT, three dimensional gas-solid two-phase flow field was simulated and analyzed for HMC-64 pulse-jet cleaned bag-type collector. The simulation data and the actual operating parameters were compared, and the airflow distribution of bag-type collector was comprehensively learned. On the basis of the original analysis, the reconstruction about flue-gas rich-lean separation combining lateral extension at the entrance of bag filter was put forward. The velocity distribution and the mass flow rate of all filter bags were compared. Results showed that through using rich-lean separation combining lateral extension, the airflow distribution of each filter bag was optimized. The integrated flow non-uniform amplitude and the relative root-mean-square value became lower than those of original model. These conclusions about the structural modification and the airflow optimization provide theoretical foundation for further research.