Business visas are usually issued to travellers visiting China on official or private business and may be issued for a single, double or multiple entries, allowing for a 30-day-stay upon each entry.
The visa will be issued within a validity window starting the day that the application is made to the Consulate and you should enter China before the expiration of this window. For single entry visas the window is 90 days, for a double entry it may be between 90 and 180 days and for multiple entry visa it may be between six and twelve months.
Transiting through China
You may not need a visa for a transit. China grants a 72 hour visa-free transit for the nationals of 45 countries travelling by air via Beijing, Chengdu, Guangzhou and Shanghai. Please look here for more information on visa-free transit.