Disclosed is a recycle fluidized-bed boiler with mixed high flow velocity and low flow velocity. The utility model comprises a furnace wall, an integral furnace hearth, an air distribution plate, an air chamber, a drum, a super-heater, a coal economizer, a separator, an air pre-heater, a solid feed recycle device and a feed recycle pipe. The utility model is characterized in that the integral furnace is divided into three sections including a furnace hearth, a first burnout section and a second burnout section by a membrane wall. The three sections are naturally and organically formed into a high temperature U-shaped separator. The upper part of the furnace hearth is small and the lower part of the furnace hearth is big, and an immersed tube is arranged on the lower part of the furnace hearth. The utility model has novel concept, reasonable design and excellent technical performance.