how much time will take the train from kashgar to fujian

Well, Fujian is a major province in China. It contains many cities. Do you wanna refer to Fuzhou?
If yes, I'm afraid that there is no direct train or flight between these two places because of the long-distance.
So you need to transfer the train in Turpan first. The duration is 17 to 21 hours.
And then take a train to Fuzhou. It takes around 2 days on the way.
Urumqi is also a good place for railway transfer.

If you though the duration is too long, you can take a plane to Urumqi first. Then transfer the flight to Fuzhou directly.

Choose the way you like.