Article 10 of the Trademark Law The following signs shall not be used as trademarks: (1) identical with or similar to the national name, national flag, national emblem, military flag and medal of People's Republic of China (PRC), and identical with the names and graphics of specific place names or landmark buildings where the central state organs are located; (2) identical with or similar to the name, national flag, national emblem or military flag of a foreign country, except as agreed by the government of that country.

However, your use within the company is temporary and limited, and it does not belong to dissemination or profit-making behavior, and will not cause damage to the copyright owner, so it is not illegal.