We tested DfuSe Demo v3.06, but it cannot find our STM32F04 (nothing can be fund). We checked the driver, USB serial device COM12 can be seen. However, STM32 ST-linke can work. Its driver is STMMicroelectronic STLink virtual COM port COM8.

[WLi.1]

..

[Tesla DeLorean]

DfuSe demo doesn't use the serial port on the ST-LINK. It needs a USB connection directly​ to the target device, and DFU support in ROM.

[WLi.1]

On windows 10, It is always auto fund in serial port. How can we solve this?

[Tesla DeLorean]

Ok, but finding the ST-LINK serial port helps how exactly?

Why are you using DfuSe Demo? Wouldn't STM32 Cube Programmer or Flash Demostrator be more appropriate?

Question also seriously lacking in contextual detail. What board? Custom? What modes of connectivity does it provide to the outside world? A schematic or system diagram would transcend language issues.

Check USB support in the boot loader for the "STM32F04" in app note AN2606