Coal-fired condensable particulate matter (CPM) has been widely studied, mainly because of its significant environmental hazards. Currently, effective CPM removal methods are lacking. Therefore, the inhibitory effect of the addition of biomass to pulverized coal on the production of coal-fired CPM was investigated. The results indicated that the production of CPM could be inhibited by the addition of an appropriate amount of biomass for co-combustion with pulverized coal. Therein, the inhibitory effect of adding cornstalk was much higher than that of adding rick husk or pine with an addition ratio of 30%. The effect of the cornstalk addition ratio on the inhibition of CPM was also studied. The results showed that the emission concentration of CPM initially decreased and then increased with an increase in the addition ratio, and that there was an optimum range of addition ratios when intending to inhibit the production of CPM during the cornstalk-coal co-combustion. Compared with the coal-fired CPM composition, the content of some components such as Br−, NO3−, K, Na, Ca, and Al decreased, while that of NH4+ and Cl− increased with an increase in the addition ratio. It should also be noted that the concentration of SO42−, which is the main substance in CPM, decreased by an order of magnitude when the addition ratio of cornstalk was 30%. The amount of aromatic compounds, the substances with the highest toxicity levels in CPM, can be efficiently reduced with approximate addition ratios including 30–50%.