Comparison of combustion and gasification behavior of waste plastics with pulverized coal is necessary to increase the replacement rate of waste plastics to coal. The combustion and gasification behavior of these materials were observed by use of rapid heating experiment and laminar flow furnace. The experimental results showed that the ignition of waste plastics was faster than that of pulverized coal when the size of these materials was same, and the combustibility of waste plastics, which size is less than 1.4 mm, was almost same as the coal. The crushability of waste plastics was studied by experiment using extruder and impact mill. The results showed that the crushability of waste plastics improved by melting and mixing of various kinds of plastics. And moreover an increase of impurity also improved it. The mechanism seems as follows. The dechlorinated residues produced by PVC dechlorination during heating process are dispersed in melting waste plastics. And the residues become the origin of the destruction during cooling process.