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

Here is Why You Need An Adapter

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

Mauritania

In Mauritania, outlets of type C are in use.

Type C

China

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

Type A

Type C

Type I