已解决,步骤如下：
//src/lang/index.js
import Vue from "vue";
import VueI18n from "vue-i18n";
import elementEnLocale from "element-ui/lib/locale/lang/en"; // element-ui lang
import elementZhLocale from "element-ui/lib/locale/lang/zh-CN"; // element-ui lang
import enLocale from "./en";
import zhLocale from "./zh";

Vue.use(VueI18n);

const messages = {
en: {
...enLocale,
...elementEnLocale
},
zh: {
...zhLocale,
...elementZhLocale
}
};

const i18n = new VueI18n({
// 设置语言 选项 en | zh
locale: localStorage.getItem("language") || "en",
// 设置文本内容
messages
});

export default i18n;

在组件中引用：
import i18n from '@/lang/index'

data() {
i18n: i18n
}