The invention discloses pleuromutilin derivatives with the structure as shown in a formula (I) in the specification and the antibacterial activity, salts, solvates, optical isomers and polymorphism compounds thereof acceptable in pharmacy and/or veterinary medicines as well as a preparation method and an application of the pleuromutilin derivatives and the salts, solvates, optical isomers and polymorphism compounds thereof in antibacterial compositions. The preparation method has the beneficial effects that two different lead compounds are connected together by covalent bonds so as to generate a synergistic effect, an additive effect or new pharmacological activity in vivo; sulfonamides are spliced into side chains of pleuromutilin so as to generate new pleuromutilin derivatives, the antibacterial activity of the obtained new compounds can be enhanced, the obtained new compounds have obvious antibacterial activity for gram-positive bacterium, gram-negative bacterium and mycoplasma and an obvious inhibiting effect on drug-resistance bacteria such as MRSA, and the antibacterial spectrums of the obtained new compounds are effectively expanded.