LM25117: If I add the 4.7R resistor between the SW PIN and the middle of the bridge arm（the middle of high side and low side MOSFET）

Hello Hope,

You will slow down the turn off time of the high side MOSFET, when slowing down transition times we slow down the high side turn on, not off. By implementing as mentioned, you will also create a larger voltage drop when the Boot cap is powering the high Side gate driver. It is not recommended as you could potentially engage the Boot UVLO threshold prematurely? If you are trying to slow down transition times, you should use a gate drive resistor in series with Ho and high side gate of the MOSFET, or put a resistor in Series with the Boot Cap to the Boot pin. i.e. place a resistor from Boot Cap +ve to Boot pin.