The invention discloses an alkali treatment method for bagasse forcattle feeds. The alkali treatment method is characterized by comprising the following steps: smashing and screening the bagasse, adjusting the smashed and screened bagasse till maintaining proper moisture content, soaking the bagasse in an alkali solution, and squeezing to remove the alkali solution through squeezing equipment. The cellulose content of the bagasse pretreated by the method is increased by 80.1 percent, and the lignin content is reduced by 52.4 percent, so that the removal of the cellulose and the lignin is obvious. Therefore, the compact structure of lignin, cellulose and hemicelluloses of the bagasse treated by the method is damaged, so that the cellulose hydrolysis rate is increased, the enzyme-resistant characteristicof the bagasse is improved, and an obtained bagasse material can be directly used as coarse feeds for beef cattle or is treated by microorganisms to obtain a product with higher additional value, so that biomass resources such as the bagasse can be effectively used; furthermore, according to the alkali treatment method, the shortcomings of high alkali consumption, insufficient alkali mixing and low alkalization efficiency in the conventional bagasse alkali treatment are overcome; meanwhile, the alkali treatment method is small in investment, safe and easy to operate.