The invention relates to a foam type disinfectant for farms as well as a reparation method and application thereof. Every 100 parts by weight of disinfectant comprises the following components in parts by weight: 5 to 10 parts of active chlorine, 5 to 10 parts of aldehydes, 25 to 40 parts of foaming agent, 1 to 2.5 parts of enhancer, 0.1 to 0.5 part of buffering agent and the balance of water; during preparation, the components are weighed according to the proportion and are mixed uniformly; and the disinfectant and water are mixed according to the volume ratio of 1:(100-1000) to be applied todisinfection of the farms. Compared with the prior art, the disinfectant has the following advantages: foam is ejected through a high-pressure foam ejector, the foaming multiples reach more than 100,the disinfecting surface can be covered completely, dead angle and blank are avoided, the disinfectant is distributed uniformly, and the contact time of the disinfectant and the disinfecting surfacecan be prolonged, so that the disinfecting effect is enhanced; and meanwhile, water can be saved, and the foam type disinfectant for the farms is suitable for cleaning and disinfecting colony houses and devices in the farms.