In my case, I first use the /home/werner/.popt file to define the alias -
Z as follows:

$ cat /home/werner/.popt  
rsync alias -Z --no-p --no-g --chmod=ugo=rwX

Then I run rsync with the alias -Z like this:

$ rsync -avZ --temp-dir=/tmp /media/cdrom/pool/ /home/werner/Desktop/111/

Now, suppose I want to do some more complicated job including the above
codes in it, I think it's a more easier way first define the
alias_varialbe in the script then invoke it by using rsync command in the
same script.  I just want to know how to do the above things like this
way.

BTW, as you have pointed that, we can simply invoke the rsync like for my
purpose:

rsync -av --no-p --no-g --chmod=ugo=rwX --temp-dir=/tmp /media/cdrom/
pool/ /home/werner/Desktop/111/

But for a more complicated case, say, I want to do server different rsync
jobs with different alias options in one script, according to the
described method here, I must define all of the  alias options in  /home/
werner/.popt, in this way, I must remember all of the these definitions
in mind when I want to invoke them.  While if I can define these alias
options in-place of the shell script which use all of these alias
options, I think it will be more convenient to use.

Regards