The utility model relates to a partition wall inside a boiler, in particular to a return partition wall inside a return device of a circulating fluidized bed boiler, which comprises the partition wall and is characterized in that prefabricated beams are arranged under the partition wall, reinforcement bars are added inside the prefabricated beams which are A type high strength wear-resistance pouring materials; the reinforcement bars are composed of U-shaped transverse bars and vertical bars, and connecting bars are arranged at the positions where the transverse bars and the vertical bars are connected; the reinforcement bars adopt heat-resisting materials such as 1Cr20Ni14Si2 or 0Cr25Ni20 of a higher level. The return partition wall not only can realize high flow rate, low energy consumption, self-balancing-return, but also effectively solves the problem that the return partition wall falls off.