G code how to walk joints ？？

Can g code meet my requirements? Move in joint position instead of "xyzabc"

If you are using version 2.9 then the answer is yes. The feature is called "switchable kinematics":
linuxcnc.org/docs/devel/html/motion/switchkins.html

This allows you to switch between world- and joint-mode by calling a custom M-Code.

There is a simulation config in version 2.9 with a 6 axis industrial manipulator that should help you: /configs/sim/axis/vismach/melfa-sim

If you want to look at that before you install 2.9:
github.com/LinuxCNC/linuxcnc/tree/master...is/vismach/melfa-sim

I have that same robot here in my shop and it works perfectly. Make sure to read the various comments in the above simulation config.

I downloaded the file you gave me, put it on the desktop, open it with the terminal, and found an error. Is this caused by version 2.8.2?

What I meant is that you might want to browse the linked simulation config folder to read the various comments. For example how to switch from world to joint mode in G-Code in the "example.ngc" or the M-code remaps (M428, M429) in the folder "remap_subs".
To actually run the sim config you will need to install version 2.9 (see below) and then you will find the linked config in the config selector to run it.

Are there any other methods that have similar effects?

Not that I know of.

If I want to upgrade to linuxcnc 2.9, what should I do? 

You can install the current development version 2.9 as a deb install:
buildbot.linuxcnc.org/

Or you can get the sourcecode from the github site and build locally on your machine. This can become a somewhat involved process as you might need to manually install packages that linuxcnc depends on (called a RIP install).