Lead-based perovskite nanocrystals are widely used in luminescence due to their exceptional properties. However, the toxicity of lead impedes their prospective commercial applications. Recently emerged lead-free CsEuCl3 nanocrystals exhibit outstanding monochromaticity, but have relatively low photoluminescence quantum yield (PLQY). In this study, we successfully synthesized CsEuBr3 nanocrystals characterized by high PLQY and monochromaticity. The photoluminescence (PL) emission peak is located at 421 nm, with a full-width at half maximum (FWHM) of approximately 21 nm, and a PLQY of 70 %. We have verified that the synthesized material is CsEuBr3 nanocrystals based on its characteristics in terms of structure and spectrum. Moreover, a dopant-driven growth model for CsEuBr3 is proposed, which highlights the critical role of Eu2+-2OAm and oleic acid (OA) quantity in synthesis. Elucidating the growth mechanism of CsEuBr3 nanocrystals holds significant importance for advancing research in novel lead-free perovskite materials.