The invention provides a method for improving the bonding strength of a titanium alloy baked porcelain tooth inner crown and metal-porcelain, a 100 to 200 mu m protective permeation layer is preparedon the surface of the titanium alloy tooth inner crown through complex permeation chemical heat treatment of B-N-ZrO2 doped with mixed rare earth on the surface of the titanium alloy tooth inner crown. The formula of a complex permeation agent comprises the following component in percentage by mass: 3% to 5% of B4C, 2% to 4% pf (NH2)2CO, 5% to 8% of KBF4, 5% to 10% of nanometer ZrO2(particle sizeof 50 to 100 mu m), 1% to 2% of mixed rare earth (including 50% of Ce, 20% of La, 18% of Nd and the rest of Pr in percentage by mass), and the rest of NaF; and the process conditions are: Maintainingthe temperature at 550 to 650 DEG C for 3 hours, then raising the temperature to 850 to 920 DEG C and maintaining the raised temperature for 6 hours. The method provided by the invention is simple, and can effectively improve the bonding strength of a titanium alloy tooth inner crown and dental porcelain metal-porcelain.