Thank you very much everyone!!!
Sorry I cannot reply one by one, so I'll say things in one post.
The current do flow between by hands because another hand is touching a ground line and feel pain.
My hand was a little wet because of working, so I think the resistance won't be too high.
I'm currently living in China, so it's 220v AC.
I did not feel stick to it, nor bounce away, nor burn, I can even remember that second clearly and I move away my hand using my mind, not muscle reflect. I feel so strange...
I usually very careful, but these days I was working on a computer power supply without the metal case, I first thought it's a 110v line inside, but I'm sure it's 220v later because I feel the same touching the plug directly, but without touching the ground line this time.
I don't know if there should be a "electronic leaking protect" switch that should cut off the power somewhere in the house, however it never react.
Thank you everyone again, I will be careful next time.