I am unable to determine the exact identity of the episode you describe that was used in the CCTV public service announcement, because this information is highly uncertain. However, I can give you some similar clues that will hopefully help you find the song you need.

CCTV public service advertisements often use some well-known songs or original music as interludes. This music can usually touch people's emotions and convey the message to be expressed in the advertisement.

For example, on the Spring Festival Gala in 2017, after the skit "Wife" performed by Cai Ming and Pan Changjiang, a public service announcement "Love Wants Together" was played, and the episode used in it was "If the Cloud Knows", and This episode is a classic old song from Wanfang.

In addition, some public service advertisements use famous classical music as the soundtrack, such as "Going Home" (the "Spring Festival Overture" is used), "Dream Baby" (the "Jasmine" and "Jasmine" are used as the soundtrack) "The Fishing Boat Sings Evening") and so on.

If you can provide more details, such as the time when the advertisement was released, the specific scene where the episode was used, etc., I may be able to provide you with a more accurate answer.