The invention relates to an air purifying agent which comprises the following raw materials by mass: kieselguhr powder, zeolite powder, medical stone powder, tourmaline powder, activated carbon power, sepiolite powder and titanium dioxide powder. The air purifying agent is prepared by the steps of (1) mixing the kieselguhr powder, the zeolite powder, the medical stone powder, the tourmaline powder, the activated carbon power, the sepiolite powder and the titanium dioxide powder; (2) granulating a mixture obtained in the step (1); and (3) drying the granulated mixture obtained in the step (2). The air purifying agent disclosed by the invention is large in specific surface area and uniform, has a good effect for adsorbing and decomposing harmful substances in air and is an ideal selected material suitable for environment purification in closed spaces such as a room and an automobile and for various air purifiers.