The invention relates to an expansion and solidification type plugging agent which comprises the following components in parts by weight: 0.5-2 parts of a calcium sulphoaluminate expanding agent, 1-4 parts of polypropylene fibers, 0.1-1 part of a water adsorption expansion type polymer, 1-5 parts of super absorbent resin SAP, 2-6 parts of puffed starch, 2-6 parts of salt-resistant clay, 20-40 parts of calcium carbonate and 0.1-0.5 part of high viscosity polyanionic cellulose PAC-HV. The preparation method comprises the following steps: sequentially adding the components in parts by weight to a kneading machine by a conventional preparation method under normal temperature and pressure; uniformly mixing and stirring; and crushing to a particle product with the grain size of 0.01-0.5mm till being dried. The plugging agent provided by the invention has the characteristics of high expansion rate, viscous flow capacity, plugging capacity, strong salt-resistance, flowability, pumpability, good coagulability, simple process, safe and quick construction, long coagulability, wide source of raw materials, high plugging success rate and the like, and is widely applied to plugging processes of large pore paths, subterranean rivers and great Karst cave leakage strata in petroleum and geological drilling.