The invention discloses small-porosity glass ceramic for dental implant. The glass ceramic comprises, by weight, 50-70 parts of silicon dioxide, 20-70 parts of magnesium oxide, 30-40 parts of calcium hydrophosphate, 20-30 parts of phosphorus pentoxide, 15-25 parts of silicon carbide, 10-20 parts of zinc, 12-20 parts of polytetrafluoroethylene and 30-40 parts of ethocel. The preparation method includes: evenly mixing silicon dioxide, magnesium oxide, calcium hydrophosphate, phosphorus pentoxide, silicon carbide, zinc, polytetrafluoroethylene and ethocel, melting prior to heating to 1300-1400 DEG C, and performing reaction for 2-3h; performing shock cooling, smashing, sieving and cold press molding; performing sintering. Powder is formed and made prior to being prepared into the glass ceramic, so that structural glass can be prevented from cracking as being directly formed, and product quality is improved; the product prepared through the method is small in porosity and tight without cracks.