The invention relates to a process for growing an ONO (oxide-nitride-oxide) capacitor structure. The process comprises the following steps: a. providing a semiconductor substrate; b. growing 20-24nm-thick bottom oxide layer on the semiconductor substrate through dry oxidation; c. depositing an intermediate SiN layer with thickness of 20-24nm on the bottom oxide layer on the semiconductor substrate; and d. growing a 270-330nm-thick top oxide layer on the intermediate SiN layer through thermal oxidation. The process has the following advantages: the bottom oxide layer is grown on the semiconductor substrate through dry oxidation, so the dense oxide layer can be formed on the semiconductor substrate to ensure the quality of the bottom oxide layer; the intermediate SiN layer is deposited on the bottom oxide layer and the top oxide layer is formed on the intermediate SiN layer through wet-oxygen oxidation, thus forming the ONO capacitor structure on the semiconductor substrate; the top oxide layer can be rapidly formed on the intermediate SiN layer through wet-oxygen oxidation and the quality of the ONO film is ensured; the operation is simple; and the universal semiconductor pre-equipment can be adopted as the diffusion equipment and the LPCVD (low pressure chemical vapor deposition) equipment, the controllability is strong and the process steps are simple.