The invention discloses a compound sulfamonomethoxine / compound sulfamonomethoxine sodium injection which is prepared from main components and auxilary components, wherein the main components comprise 5-20 parts by weight of sulfamonomethoxine / sulfamonomethoxine sodium, 1-4 parts by weight of diclofenac sodium and 1-4 parts by weight of trimethoprim and the auxilary components comprise 0.2-0.4 part by weight of antioxidant, 40-70 parts by weight of organic solvent, 0.2-1 part by weight of regulating reagent and 10-20 parts by weight of water for injection. The injection prepared by the invention can provide effective treatment on secondary infection and mixed infection of streptococcicosis, toxoplasmosis, eperythrozoonosis, colibacillosis, asthma and other diseases, has obvious effect if applied for a long term, strong effect enhanced by several times or dozens of times, hardly generates drug resistance and has the advantages of less consumption, less application times, little irritation and quick treatment effect, can treat both symptoms and root causes, save production cost, improve product additional value and reduce toxic or side effects caused by mismatching of medicaments during treatment.