Abstract: The energy conversion property of beta-voltaic battery is not only decided by the material and structure of energy conversion device and the kind of radiation source, passivation layer also has significant influence on the radiation resistance and the initial output property. In order to realize the optimized passivation property in plain c-silicon PN beta-voltaic battery with tritide titanium source (tritium beta-voltaic battery), three kinds of passivation layers were designed to testify the radiation resistance and initial output properties. The radiation damage from the X-ray emitted from tritide titanium source was investigated individually. The initial output properties from the optimized to worst rank are as follow: Si/SiO₂/Si₃N₄ structure>Si/B-Si glass/Si₃N₄ structure>Si/Si₃N₄ structure, and for the radiation resistance, Si/Si₃N₄ structure>Si/B-Si glass/Si₃N₄ structure>Si/SiO₂/Si₃N₄ structure, and the Si/B-Si glass/Si₃N₄ structure has the optimal radiation resistance under the pure X-ray irradiation. The X-ray emitted from tritide titanium source is the main reason for radiation damage and the results from XPS detection show that the surface of c-silicon is broken by pure X-ray irradiation.