The invention discloses self-crosslinking type LED package adhesive resin and a preparing method thereof. According to the preparing method, 100-105 weight parts of phenyltrimethoxysilane, 100-120 weight parts of diphenyldimethoxysilane, 10-20 weight parts of methyl-vinyl-cyclosiloxane, 30-50 weight parts of disiloxane, 20-60 weight parts of distilled water, 100-200 weight parts of solvent and 0.03-0.05 weight part of catalyst are sequentially added to a container, constant-temperature stirring is conducted for 3-5 h at 60-80 DEG C, stirring reaction is conducted for 4-8 h after temperature is increased to 100-120 DEG C, the pH value of obtained reaction liquid is adjusted to be 7, then reduced pressure distillation is conducted so as to remove the solvent and residual water, and finally the self-crosslinking type LED package adhesive resin high in light transmittance and refraction index is obtained. The resin can achieve self-crosslinking curing reaction under a certain condition, and the thermal decomposition temperature of a cured product is quite high.