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

Here is Why You Need An Adapter

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

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M

China

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

Type A

Type C

Type I