This invention relates to an apparatus and a method for multistage hierarchical pyrolysis and gasification of solid fuels. The apparatus comprises a feeding device 1, a multistage fluidized bed reactor 6, a residual discharging valve 9, a cyclone 10 and a condenser 11. A gas inlet is provided at the bottom of the multistage fluidized bed reactor 6 and a number of stages of fluidized beds 3 are provided within the multistage fluidized bed 6, wherein the fluidized beds 3 are separated by a number of perforated distributors 5. The top stage fluidized bed 3 is connected with the feeding device 1 and the coal fed thereto is heated by char obtained from pyrolysis in this stage and the mixture of high temperature ascending pyrolysis and gasification gas to undergo pyrolysis reactions at low temperature, thereby to obtain solid particles after preliminary pyrolytic process. The solid particles flow downwards through an overflow standpipe 4/the perforated distributor 5 to the next stage of the fluidized bed and then are pyrolyzed through being heated by char and the mixture of pyrolysis and gasification gas. The solid particles in turn pass into the next stage of the fluidized bed and finally enter into the bottom stage fluidized bed to undergo gasification reactions. More light fractions in tar can be produced using the present apparatus and method.