How many days single entry tourist visa valid from the issu date...?

Usually the validity of a Single Entry "L" visa is 90 days from the date of issue. This means the holder of the visa shall enter China no later than 90 days from the date of issue, otherwise the visa will be expired and is null and void. Normally the duration of stay of a "L" visa is 30 days, which means the holder of the visa may stay in China for up to 30 days from the date of entry. If your estimated stay in China is longer than 30 days, please make it clear in the application form and ask for the Visa Officer's approval when you submit your application..