I input 5v to pro mini pin,but VCC pin output only 3v power , I think it should be 5v in VCC .
The Arduino Pro Mini can be powered with an FTDI cable or breakout board connected to its six pin header, or with a regulated 3.3V or 5V supply (depending on the model) on the Vcc pin. There is a voltage regulator on board so it can accept voltage up to 12VDC. If you're supplying unregulated power to the board, be sure to connect to the "RAW" pin on not VCC.
The power pins are as follows:
RAW. For supplying a raw voltage to the board.
VCC. The regulated 3.3 or 5 volt supply.
GND. Ground pins.