The invention discloses a gasification system for preparing cyclohexanone oxime in caprolactam by Beckmann gas phase rearrangement, which comprises a high-pressure material distribution kettle, wherein the high-pressure material distribution kettle is connected with an inlet on an upper end of a gasification tower through a pipe; a spray nozzle connected with an air pipe and a nebulizer connected with a nitrogen pipe are respectively arranged inside the inlet; an input end of the gasification tower is communicated with the air pipe of the spray nozzle; the nebulizer is arranged below the spray nozzle; an outlet on a lower end of the gasification tower is connected with the inlet on the lower end of a fluidized bed heater through the pipe; the outlet on the upper end of the fluidized bed heater is connected with the inlet of a condenser through the pipe; the outlet of the condenser is connected with a material collecting kettle; and the material collecting kettle is connected with a fractional condenser. The system can remarkably decrease coking speed and carbon deposition speed, and reduce the economic loss caused by the coking phenomenon and cyclohexanone oxime decomposition in a gasification process as much as possible, and at the same time avoids the possible factors of catalyst poisoning.