The invention relates to modified solid epoxy resin with high glass transition temperature and high tenacity. The modified solid epoxy resin is prepared from the following components in parts by weight: 100 parts of epoxy resin, 50-120 parts of a modifier, 0.05-5 parts of a catalyst, and 25-100 parts of a curing agent. The invention further provides a preparation method of the modified solid epoxy resin with high glass transition temperature and high tenacity. The modified solid epoxy resin has the excellent properties that the glass transition temperature is 128-178 DEG C, the cathodic cathodic disbonding radius is smaller than or equal to 10 mm (1.5 V, 92-98 DEG C, 28d), the modified solid epoxy resin can pass a bend test of 3 degrees at minus 30 DEG C as no crack generates, the softening point is 96-115 DEG C, the epoxide number is 0.19-0.275 mol / 100g, and the functionality degree is 2.6, so that the modified solid epoxy resin can be applied to the fields of petroleum and gas long-distance pipelines, urbane groundwater, gas pipe network pipelines, transportation industry (automobiles and ships), oceanographic engineering, corrosion prevention in bridges and construction reinforcing steel bar, and the like in which the use temperature is higher than 95 DEG C.