hi i have visa from Pakistan to china, but i have no idea to travel from Pakistan to yiwu.

Well, do you start from Islamabad?
If yes, no direct flight runs to these cities. Since you wanna travel these three cities, it's suggested to go to Guangzhou first, which makes the transportation more convenient.

Fly to Urumqi first and transfer to another flight to Guangzhou. After that, there are many bullet trains at Guangzhou South Railway Station to Shenzhen or Zhuhai. After touring around these two cities, both of them have direct flights to YW.