Oh I solved the issue now.
The story is, today I changed a display setting in nvidia controller. I set nvidia output 10 bit color depth to my monitor Dell U2720QM , because it has the ability to show 10 bit color depth.
And at the same time, XD just show me to update, so I update XD.
After XD finished update, then the issue happened.
I try a lot of way to test the bug, and at last I find when I change the color depth to 8bit in nvidia controller, then XD shows ok now.
Then I test to set the color depth in nvidia controller to 10 bit back , XD meet the same color palette issue .
So I think there maybe some issue with XD's color depth.