Abstract: Aimed at the characteristics of much crushed coal and soft coal seams in an outburst coal seam, pressure injection with solidified liquid was used to reinforce coal bodies and plug methane channels for reducing or eliminating gas outburst. A composite slurry was prepared by remixing cement with polymer latex, which breaks through the limit of present injection materials for coal bodies. The material match of the composite slurry and the strength, dry shrinkage, compactness, water retention and viscosity of the induration were tested by laboratory experiment. The best material match was selected to reinforce coal particles, and the experimental result indicates that the conglomerated coal particles have better mechanical strength and reinforcement effect. Used to reinforce coal bodies, the composite slurry has the characteristics of good viscosity, large reinforcement capability, low material cost and no pollution.