The invention discloses a manufacturing method of a SONOS device. The method comprises the steps that a shallow trench is formed in a semiconductor substrate; a formation area of a storage region is opened by photo-etching, and deep well injection is carried out; an oxide layer is filled into the shallow trench to form a first sacrifice oxide layer; a first photoresist graphic is formed by photo-etching to open a formation area of a storage tube, and the first photoresist is injected into a channel region for forming the storage tube; the first sacrifice oxide layer and then the photoresist are removed from the formation area of the storage tube; an ONO layer is grown; a formation area of a P type device is opened by photo-etching, the ONO layer in the opened area is removed, and a channelregion for forming the P type device is injected; a formation area of an N type device is opened by photo-etching, the ONO layer of the opened area is removed, and a channel region for forming the Ntype device is injected; the first sacrifice oxide layer is removed, and a gate dielectric layer outside o the storage tube is formed; and a polycrystalline silicon gate is formed. Thus, a mask for defining the ONO layer independently can be omitted, and thus, the technical cost can be reduced without changing performance of the device.