You Do Need power plug adapter while traveling from Western Sahara to China.

Here is Why You Need An Adapter

The outlet and plug type used in China are A, C and I and in Western Sahara are C and E. This is how they look like.

Western Sahara

In Western Sahara, outlets of type C and E are in use.

Type C

Type E

China

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

Type A

Type C

Type I