Epitaxial lateral overgrowth (ELO) of diamond film with SiO2 stripe mask has been carried out through microwave plasma chemical vapor deposition systems. To solve the peel-off of SiO2, this study evaluates different kinds of metal buffer layers and chooses Ir as the optimal metal. The effects of the interface feature of two types of stripe masks (Ir/SiO2 and Ir/SiO2/Ir stripes) on the internal stress status and the fluorescence properties are characterized. The optical image confirms that the diamond emerges in the interval of stripes at the initial growth stage and then forms a continuous film with smooth surface and step-flow mode after 37 h lateral overgrowth. Photoluminescence (PL) mapping demonstrates that the SiO2 mask is etched by H2 plasma and results in a high SiV− intensity, especially above the mask. The Ir cap layer on the Ir/SiO2 mask surface is effective in preventing the SiO2 from being etched in the plasma atmosphere, greatly alleviating the PL intensity of the SiV− color center compared with that of the Ir/SiO2 mask. In addition, the Ir cap layer can suppress the stress in the epitaxial layer. The findings of this study can advance the existing research on ELO technology and be potentially applied to vacancy-related color centers.