The invention discloses a catalyst for hydrolyzing active carbon-based COS under the condition of low temperature and a preparation method thereof, wherein a carrier of the catalyst is active carbon, and active compositions of the catalyst are alkali materials and metal oxide. The catalyst can remove COS in air at a low temperature (between 30 and 100 DEG C) and remove H2S generated by hydrolysis together. The preparation method comprises the following steps: firstly, using running water and distilled water to wash the active carbon, and drying the active carbon for 2 to 4 hours at a temperature of between 110 and 180 DEG C, wherein the active carbon can be coal and coconut husks; secondly, using a 1 mol/L KOH solution to boil the washed active carbon for 1.5 to 2 hours, performing modification treatment, and using distilled water to wash the solution until the pH value is approximately 6.0; thirdly, selecting one or more metallic salt solutions to soak the active carbon, performing modification treatment, and performing ultrasonic soakage for 0.5 to 1 hour, wherein the content of a soaking liquid is 10 to 90 percent of the mass ratio of the active carbon, and the volume of the soaking liquid is as follows: 20 milliliters of the soaking liquid is added into 10 grams of the catalyst; fourthly, drying the soaked active carbon for 2 to 6 hours in a 120 DEG C constant-temperature drying cabinet, and activating the catalyst for 2 to 4 hours under the protection of 300 to 600 DEG C N2; and fifthly, performing ultrasonic soakage on the activated catalyst in the fourth step in an alkali solution for 0.5 to 1 hour.