The invention discloses an SOI material using a nitride film as an insulating buried layer and a preparation method thereof, and belongs to the field of manufacturing technology of semiconductor materials. A composite nitride insulating film with good thermal conductivity and compact structure is prepared using a PECVD method and combined with hydrogen ion implantation, wafer bonding, annealing, polishing, microwave cracking and other processes to prepare an SOI structure using silicon oxynitride/ silicon nitride/silicon oxynitride composite film as an insulating layer. The thermal conductivity of the SOI material is superior to that of the SOI using the conventional SiO2 as an insulating buried layer SOI, and the SOI material is more suitable for high-temperature and high-power SOI circuits. In addition, the dielectric constant of silicon nitride is greater than that of SiO2 and the silicon nitride can be used as a gate dielectric candidate material.