National Emblem and National Flag of the Republic of China Act Article 9

When the national flag is used with a foreign flag, the flags' size and the poles' lengths must be equal. The national flag shall be placed to the right of the foreign flag. The foreign flag shall be placed to the left of the national flag. If the flags cross each other, the pole of the national flag shall be on the top.When the national flag is used together with any other flag, the previous Paragraph shall apply mutatis mutandis.
中文原文 中華民國國徽國旗法第9條
國旗與外國旗並用時,旗幅之大小,及旗桿之長短,須相等。
本國旗居外國旗之右,外國旗居本國旗之左,交叉懸掛時,國旗旗桿居上。
國旗與其他旗幟並用時,準用前項規定。

English translation for reference only; the Chinese text prevails. Not legal advice.