Hi @Boyin_Zou,
Our resident AppleScript guru @ccstone just recently provided an example of how to manipulate the Wi-Fi menu bar item and select the network you want without using any found image actions whatsoever:
As he says in the post, the script that clicks on the Wi-Fi icon is written with an English language system in mind, so you may need to make adjustments for Chinese, but this should certainly help get you on your way.
As for your other questions, the high CPU load is because you are using a lot of different "Find image" actions in your macro, an inherently CPU-intensive process that is made more intensive by searching the entire screen, as you currently have the actions configured. Generally, "Find image" is best used as a last resort when it comes to automation, preferably with its search scope limited by screen area or window (and no, it seems there is, unfortunately, no way to set a timeout for this action).