The utility model discloses a regenerative fluidized bed reactor which comprises an air chamber, a reaction chamber, a separator, a material returning device and a steam generating device, the steam generating device comprises a steam pocket and a water cooling wall, and the reaction chamber is divided into a regenerative combustion area, a soaking oxidation area and a separation back-mixing areafrom bottom to top; an air distribution plate is arranged between the air chamber and the heat storage combustion area, a primary air inlet is formed in the bottom of the air chamber, a separation binof the separator is arranged in the separation back-mixing area, an outlet in the bottom of the separator penetrates through the outer wall of the reaction chamber through a material return pipe to be communicated with one end of a material return device, and the other end of the material return device is communicated with a material return opening of the heat storage combustion area. By adjusting the structure of the reaction chamber, stable coal slime oxidation temperature can be provided, low-calorific-value coal slime solid waste with large ash content and small particle size can be treated, innocent treatment is achieved, and efficient resource utilization is achieved. Pure coal slime can be used as a raw material for oxidation incineration to recover heat, the coal slime oxidation efficiency and the device heat efficiency are high, and long-period stable operation can be achieved.