The invention relates to modified polyphenyl ether resin, a preparation method thereof and a resin composition comprising the modified polyphenyl ether resin. Particularly, the modified polyphenyl ether resin has a structure shown as the formula I, wherein R, Y, PPE, Z and c are described in the paper. The invention further discloses a product of the resin composition. By the modified polyphenyl ether resin, good glass transition temperature, high heat resistance and low (good) thermal expansion and dielectricity can be achieved.