Side wall reinforcing plate, vehicle body frame assembly and vehicle

The utility model discloses a side wall reinforcing plate, a vehicle body frame assembly and a vehicle. The side wall reinforcing plate comprises a column A reinforcing plate and a column A upper edge beam, a downward extending section extending downwards is arranged at the front end of the column A upper edge beam, the lower end of the downward extending section is connected with the upper end of the column A reinforcing plate through tailored blank laser welding, and the downward extending section is provided with a first fixing part used for being fixed to the rear end of a thumb beam. The A column reinforcing plate is provided with a second fixing part used for being fixed to the rear end of the thumb beam. According to the side wall reinforcing plate, the A-column reinforcing plate and the A-column roof side rail are in surface connection through laser tailor-welding, the connecting range between the A-column reinforcing plate and the A-column roof side rail is widened, meanwhile, the tailor-welding posi