I would like to know how many days takes to get a tourist visa in Kathmandu for China

Usually, it takes four working days to issue the visa. If the visa is needed earlier, additional urgent fee will be charged.

A single-entry tourist visa generally permits 30 days stay duration, if you want to stay in China for more than 30 days, please make it clear in the application form and ask for the Visa Officer's approval when you submit your application.