Service system for foreigners working in China
According to the Administrative law of the People's Republic of China,the foreigners who have the work permits are requried to submit the Applying for an Extension for renewal 30 days ahead of the expiration of their permits.It will be implemented from 28 Feb 2018.Those who didn’t handle it on time, it is not allowed to make the extension.

1. The announcement was issued by State administration of foreign experts affairs of the People's Republic of China, not by the local administration.
2. If the the foreigners who have the work permit submit the Applying for an Extension for renewal in 30 days or after the expiration of their permits, it will be denied of renewal and shall apply a new one.
Check on the above Letter of Approval for Administrative License,The last sentence of this paragraph, you can see the period of validity.
Scan the QR code on your work permit to check the period of validity, you can see your detail information.
Usually the required time for the extension of work permit and residence permit is

So it is necessary to apply the work permit earlier,here is a suggestion for you:
(I)If your work permit is going to be expired, please apply for extension 40 days earlier before the expiration of your work permit, don’t do it on the same day it expires, there is way to do it.
(II)Please pay attention on the official holidays, such as:
1.New Year Day from 30th Dec 2017 to 1st Jan 2018
2.Chinese New Year Spring Festival,from 15th Feb to 21st Feb 2018
3.Qingming Festival Day,from 5th April to 7th April 2018
4.International Labour Day,from 29th April to 1st May 2018
5.Dragon Boat Festival Day,from 16th June to 18th June 2018
6.Mid-Autumn Festival Day,from 22nd Sep to 24th Sep 2018
7.National Day,from 1st Oct to 7th Oct 2018
Please note that, the above time is not including the Making Appointmentsin immigration.