Stripline question

One trace route between two ground layer formed a stripline structure.
If use power plane instead of one of the ground plane, is it the same ?
Thanks.

This will work almost as well. The power planes will have to be coupled to the ground planes with numerous capacitors. (This should already be done for EMI reduction)

If there is a width power trace, can I use it to form a strip line structure ?
I mean...
L1--power trace
L2--signal trace
L3--GND
Thanks.

powerplane?do you mean static voltage supply?
I think it will not disturb microwave signal propagation.Because they are differed
in frequency.They can exist just like two modes.