The invention relates to a high-strength composite submersed nozzle combined with silicon carbide crystal whiskers. The high-strength composite submersed nozzle comprises an outer layer body, an outer layer slag line segment, an inner layer and a boundary layer; the boundary layer is composed of, by weight, 40-60% of one or two kinds of white corundum and tabular corundum, 3-10% of calcined alumina, 15-40% of one or more kinds of SIALON, ALON and silicon nitride and boundary sols accounting for 8-10% of raw materials of the boundary layer in weight; the boundary sols are formed by mixing 60-80% of metasilicic acid ethyl esters and 20-40% of cane sugar uniformly and then treating the mixtures at 40-60 DEG C for 12-24 hours. The sols in the boundary layer react for generating the bamboo-like and reed-like beta-silicon carbide crystal whiskers with the end faces pointed at high temperature, the beta-silicon carbide crystal whiskers of the structure are embedded into the outer layer and the inner layer of the nozzle, and therefore the two composite layers can be combined closely.