The M visa is issued to those who intend to go to China for commercial and trade activities. For more information about other types of visas for China, see this page.

Application requirements

To apply for an M Visa, the following informaiton must be handed in at your nearest Chinese embassy, consulate or (in some countries) official visa processing center:

1. Completed visa application form.
2. One recent passport-size photograph with white or blue background.
3. Original, signed passport (with at least six months before expiration).
4. Evidence of previous Chinese visa (if you have previously received a Chinese visa).
5. Money for visa application fee.
6. Business letter.
7. Business invitation.

Note: Application forms for visas and authentication or notarization can usually all be downloaded from the websites of the Chinese Embassy and Consulate General in your country, or collected from the visa section in person. For example, see this page.

Validity

1. Up to 90 days for single entry.
2. Up to 180 days for double entry.
3. Up to 365 days for multiple entry.

Maximum stay per one entry in China: 30 days (remember that ‘validity’ just means how long you have to attempt to enter China on that visa from the day it is supplied, not how long you can actually spend in the country).

Can I extend my stay on this visa?

Yes, for up to 180 days.

Can I work on this visa?

Yes

source:onestop