In this paper, a class of narrow-sense constacyclic BCH codes over Fq2\documentclass[12pt]{minimal}
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\begin{document}$$\mathbb {F}_{q^2}$$\end{document} with length n=q2m-12q2-1\documentclass[12pt]{minimal}
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\begin{document}$$n=\frac{q^{2m}-1}{2\left( q^2-1\right) }$$\end{document} is studied, where q≥3\documentclass[12pt]{minimal}
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\begin{document}$$q\ge 3$$\end{document} is an odd prime power and m≥2\documentclass[12pt]{minimal}
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\begin{document}$$m\ge 2$$\end{document} is even. The maximum designed distance such that narrow-sense constacyclic BCH codes over Fq2\documentclass[12pt]{minimal}
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\begin{document}$$\mathbb {F}_{q^2}$$\end{document} with length n containing their Hermitian dual codes is determined. We obtain some new quantum codes by using such narrow-sense constacyclic BCH codes. Our constructions not only have larger designed distance but also have better parameters than the ones in the literature.