how to open multiple files without split the window?

[kingluo]

I need to open multiple files in the same window as buffers.
After ctrl-z selects multiple files, and press ctrl-o, it opens files as multiple windows, which is not expected.

[tacahiroy]

It opens files in split windows by default, you can change this behaviour using a variable, g:ctrlp_open_multiple_files.
https://github.com/ctrlpvim/ctrlp.vim/blob/fc153aabd54f9189e576c9bfb07bac09f36f2ccd/doc/ctrlp.txt

I don't understand what you want to do exactly though, you can open files in hidden buffers by setting i for the variable.
Other possible values are to open files in tabs or split windows.