Hi Wenxue,
For Device mode to wake up the PC Host, the USB device should be powered otherwise the device can not signal to the Host when you are going to wake up the system, the power option should be found somewhere of BIOS.
For PC host to wake up USB device(Kinetis MCU) in VLPS mode, you should enable asynchronous resume interrupt which is one of source for the AWIC providing the USB Voltage Regulator is on under VLPS mode, when the MCU asynchronously detects K-state using the unfiltered state of the D+ and D– pins, the USB module would send an asynchronous wakeup event to the MCU.
Hope that helps,
Best Regards,
Kan