I wrote some statements like below:

os.system(cmd) #do something
subprocess.call('taskkill /F /IM exename.exe')

both will pop up a console.

How can I stop it from popping up the console?

The process STARTUPINFO can hide the console window:

si = subprocess.STARTUPINFO()
si.dwFlags |= subprocess.STARTF_USESHOWWINDOW
#si.wShowWindow = subprocess.SW_HIDE # default
subprocess.call('taskkill /F /IM exename.exe', startupinfo=si)

Or set the creation flags to disable creating the window:

CREATE_NO_WINDOW = 0x08000000
subprocess.call('taskkill /F /IM exename.exe', creationflags=CREATE_NO_WINDOW)

The above is still a console process with valid handles for console I/O (verified by calling GetFileType on the handles returned by GetStdHandle). It just has no window and doesn't inherit the parent's console, if any.

You can go a step farther by forcing the child to have no console at all:

DETACHED_PROCESS = 0x00000008
subprocess.call('taskkill /F /IM exename.exe', creationflags=DETACHED_PROCESS)

In this case the child's standard handles (i.e. GetStdHandle) are 0, but you can set them to an open disk file or pipe such as subprocess.DEVNULL (3.3) or subprocess.PIPE.