The invention discloses a chromogenic formaldehyde adsorbing material and a preparation method thereof. The adsorbing material consists of a carrier, a high molecular organic amine polymer, a polylol polymer and a formaldehyde reaction indicator, wherein the high molecular organic amine polymer and the polylol polymer account for 1 to 50 percent of formaldehyde adsorbent, the formaldehyde reaction indicator is little, and the balance being the carrier. The preparation method thereof comprises the following steps: mixing the high molecular organic amine polymer and the polylol polymer according to mass, adding deionized water to dilute the mixture so as to prepare formaldehyde reagent; mixing the formaldehyde reagent and the formaldehyde reaction indicator; and spraying or dipping the mixed solution onto the surface of the carrier, and drying the carrier and so on. The adsorbing material and the preparation method can quickly, thoroughly and continuously remove formaldehyde pollution in indoor air until the content of the formaldehyde is reduced to safe concentration, are nontoxic, pollution-free, safe and environment-friendly to use, and can intuitively show the reaction degree of the formaldehyde.