6.31 can support x64，but 6.35 can't？
can we use chr at x86 pc？becouse i see 6.35 chr ver can  support x64

Yes there is issue with new installations of x86 on 6.35.4 We are working on fix for that. 

what x86 hardware are you running ? 
But yes CHR also is  option

i am use CCR1036 before.now,want to try x86 at CPU:E5 2670*2,networkcard:intel 82599.and running kvm to do something.becouse CCR have not kvm or metaroute

Then CHR under some VM would be better option on this new Hardware then just plain x86 RouterOS. 

i hope CCR can running kvm or metarouter。
can running small op or linux os，to do somethings。

metarouter woul dbe (atelast "potentially")implemented both on Tiler and Arm arch and already discussed/requested feature, but since Tile IP(and egineers) transition to Ez Chips then to Melanox - future of such/TIle Arch isn't clear to me.