In this paper, we studied the properties of generalized John domains in metric space. We prove that a domain $D$ is a $\phi$-John domain if, and only if, $D\mathrm{\setminus }P$ is a ${\phi }^{\prime }$-John domain, where $P$ is a subset of $D$ containing finitely many points of $D$. Meanwhile, we also showed that the union of $\phi$-John domains is a ${\phi }^{″}$-John domain in metric space.