The invention relates to a method and a device for preparing a zinc ferrite catalyst by using single-mode microwaves. The method comprises the following steps: synthesizing a zinc ferrite precursor solution from Zn(CH3COO)2.2H2O, Fe(NO3)3.6H2O, citric acid and anhydrous ethanol through a sol-gel technology; drying the prepared zinc ferrite precursor solution, grinding the dried precursor, and performing sieving separation; uniformly mixing the sieved zinc ferrite precursor with a microwave sensitizer according to a mass ratio of 1:0 to 2:7, adding the obtained mixture into a quartz tube reactor, and then placing the quartz tube reactor in a single-mode microwave reaction chamber; and carrying out calcining pyrolysis on the sol-gel technology synthesized zinc ferrite by using the single-mode microwaves. The method using the microwave radiation technology to realize rapid synthesis of an environmental functional material has the advantages of low energy consumption during calcinations, short reaction period, and realization of the rapid non-degradable organic substance adsorption of the synthesized zinc ferrite material, overcomes the disadvantages of long reaction period, high energy consumption and high cost in the prior art, and is a new method for synthesizing the zinc ferrite environmental functional material.