The invention provides a preparation method of high-strength hydrogel serving as a cartilage substitute and capable of combining with the subchondral bone. The preparation method includes: dissolvingsodium silicate, acrylamide, a cross-linking agent and sodium alginate in water to obtain a mixed solution A, dissolving soluble phosphate, the sodium silicate, the acrylamide, the cross-linking agentand the sodium alginate in the water to obtain casting membrane liquid B, scraping the casting membrane liquid B on a glass plate to form a membrane by a membrane scraping rod, pouring the mixed solution A on the membrane, flattening by scraping with the membrane scraping rod, allowing nitrogen to flow in, utilizing ultraviolet to initiate acrylamide polymerization, subjecting the membrane, alongwith the glass plate, to crosslinking in aqueous calcium ion solution, soaking in aqueous gluconic acid-delta-lactone solution to obtain high-strength hybridized hydrogel, tearing the high-strength hybridized hydrogel membrane off the glass plate, and subjecting the high-strength hybridized hydrogel membrane to crosslinking in the aqueous calcium ion solution to obtain the high-strength hybridized hydrogel which comprises calcium phosphate in a lower layer. Due to the fact that the calcium phosphate has the biological activity of inducing in-vivo bone growth, the hydrogel is capable of combining with the subchondral bone.