What are the requirements for tourist visa application? I have been visited many other countries.

For tourism to China, you need to join with others (at least 5 members) as a group to apply for a group visa to China. So, better start to contact a China travel agency like this Travelchinaguide. They are capable to provide an invitation letter and required travel itinerary. Other documents are your passport, application form, passport-sized photo, return ticket and hotel reservation. BTW, after this, you may also required to go to Chinese embassy in person to make an appointment for an interview. Copies of your visas to other countries are also helpful.