在网上查找,发现在el-radio-group中加上 fill = "#d4237a" 即可. 可以使十六进制也可以是英文名称.

 <el-radio-group v-model="tabPosition"
                          @change="handleClick"
                          style="margin-bottom: 30px;"
                          fill='#d4237a'>
            <el-radio-button label="card" >会员办卡</el-radio-button>
            <el-radio-button label="charge">会员充值</el-radio-button>
            <el-radio-button label="combo">购买套餐</el-radio-button>
            <el-radio-button label="add">追加套餐</el-radio-button>
</el-radio-group>

效果如下: