SiC photonics has been developed for over a decade, one of the major obstacles is the difficulty of fabricating ultralow optical loss SiC thin-films. Scientists in China have fabricated an ultralow loss 4H-SiCOI platform with a record-high-Q factor of 7.1 × 106. Nonlinear photonics process, including second-, third- and fourth-harmonic generations, Raman lasing, and Kerr frequency combs have been observed. This demonstration represents a milestone in the development of SiC photonic devices.