The present invention discloses a method for removing a carboxyl and hydroxyl protecting group of a β-lactam compound. The method is removing a carboxyl and/or hydroxyl protecting group from a protected β-lactam compound under the action of trichloroacetic acid and a carbocation absorbent to give a deprotected product of the β-lactam compound. The method of the present invention employs trichloroacetic acid instead of trifluoroacetic acid, and combines trichloroacetic acid with phenol or m-cresol, and anisole, greatly reducing the amount of trichloroacetic acid used. In addition, trichloroacetic acid is decomposed in the presence of water into chloroform and carbon dioxide in a subsequent process converting cephalosporin to a sodium salt, and is easy to remove, without the problem of residual trichloroacetic acid, achieving a high reaction yield and producing relatively few impurities. Trichloroacetic acid is cheap and environmentally friendly and is beneficial in industrial production due to cost reductions achieved.