What is your host OS?
What exactly is shutting down automatically? (the guest OS, the VM, Workstation, or the host OS)
And do you mean a shutdown or a crash of some sort?
my host os is Linux 3.10.0-1062.el7.x86_64 CentOS Linux release 7.7.1908 (Core)
I think it's the crash of the VM
Every time I reboot the VM, it crashes in a few hours
Your VM is losing its connection to its X server on the host:
2020-05-11T21:57:47.178+08:00| svga| E105: PANIC: XINFO IO fatal error.
You are using a very interesting X server:
2020-05-11T19:54:16.183+08:00| mks| I125: XINFO ServerVendor: "Moba/X"
2020-05-11T19:54:16.183+08:00| mks| I125: XINFO VendorRelease: 11603000
I have never seen that before! Neat!
If you are running Workstation inside an X session which is forwarded to a remote host, the network will need to be absolutely reliable, because any brief disconnection will cause a crash like this.
Check the Centos host logs to see if it mentions any problems with network connectivity at around the time of the crash. If the Moba X server also keeps logs, check those too in case they describe a problem interrupting the connection.
(EDIT: Minor clarification: It is the host's X server that we are talking about, which in this case will be running on a separate Windows machine, not the guest's X server which runs inside the VM.)