Integrating magneto-optical oxides with high figure of merit on silicon has been a long-standing challenge for nonreciprocal photonic applications in integrated photonics.In this report,several magneto-optical thin films candidates for on-chip nonreciprocal photonic device applications will be discussed.We also report a compact monolithic optical isolator on silicon based on CeYIG/Si nonreciprocal optical resonator,with isolation ratio up to 19.5dB at 1541.6 nm.