China recently put forward stronger requirements for PM2.5 emission in 2012. Electrostatic precipitators have relatively low efficiency for the collection of submicron particle, especially for PM2.5. An alternate way to increase its efficiency is to enforce the coagulation and, thereby, form larger particles. In this work, we propose an efficient way to enhance the coagulation between oppositely charged particles by using a stack coagulator. Firstly, in order to explore the impact of the bipolar charging and coagulation to the separation efficient of PM2.5, we use system modeling and simulation to explore the whole charge-coagulation-collection process of PM2.5. The results show that the coagulation rate of bipolarly charged particles can be increased by a factor of 10(2)approximate to 10(4) compared to the neutral particles and the collection efficiency of dust particles increases as the particle size grows. Subsequently, via the dust particles coagulation experiments, the emission rate chart and emission reduction charts of PM2.5 are plotted, which indicate that the average emission reduction of PM2.5 is almost 85%.