The invention provides a multilevel air-lift loop reactor with coaxial variable height multiple guide cylinders. The multilevel air-lift loop reactor mainly comprises an outer cylinder (1), a first-level guide cylinder (2), a second-level guide cylinder (3), a third-level guide cylinder (4), a central gas distributor (5), an annular gas distributor (6), a gas-liquid mixed nozzle (7), an upper discharge port (8) and a lower discharge port (9), wherein at least three coaxial variable-height guide cylinders are assembled in the outer cylinder (1) of the reactor, the central gas distributor (5) is installed on the bottom of an air-lift central round space, the annular gas distributor (6) is installed on the bottom of an air-lift guide cylinder annular space, the air-liquid mixed nozzle (7) is installed on the lower part of the air-lift guide cylinder annular space, so that the suction force is formed, the air-liquid circulation power is enhanced, and the cross sections of the annular spaces which are formed among a plurality of guide cylinders are not the same. According to the multilevel air-lift loop reactor, the heights of the plurality of guide cylinders are different, so that fluid can form good ordered circulation flowing from the inside to the outside. The multilevel air-lift loop reactor with the coaxial variable height multiple guide cylinders provided by the invention is suitable for chemical reactions with low height-diameters and large handling capacity.