You Do Need power plug adapter while traveling from China to Cocos (Keeling) Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Cocos (Keeling) Islands is I and in China are A, C and I. This is how they look like.

China

In China, outlets of type A, C and I are in use.

Type A

Type C

Type I

Cocos (Keeling) Islands

In Cocos (Keeling) Islands, outlets of type I are in use.

Type I