Using ion exchange fiber fabric as purification material, a new type of air purifier was developed. Based on Bernoulli’s equation, the pressure distribution in the airway of the new harmful gas purifier is theoretically analyzed, and the equation reflecting the distribution of static pressure in the rectangular channel of the purification unit is established, and then the distribution of filtration speed along the path is studied, on this basis, the functional relationship between the pressure difference on both sides of the filter material and the initial velocity of the inlet of the purification unit is established, and the theoretical calculation formula of the total resistance of the purification unit and the purifier is derived, which can reflect the influence of various parameters of the purifier on the resistance, which provides a theoretical basis for subsequent research.