The invention discloses a compound Chinese herb preparation capable of improving disease resistance of tilapia. The compound Chinese herb preparation is mainly prepared from, by mass, 1-20 parts of gallnut, 1-20 parts of pericarpium granati, 1-20 parts of sappanwood and 1-20 parts of roots of red-rooted salvia. The invention further disclose the application of the compound Chinese herb preparation in preparing medicine having the effects of restraining aeromonas hydrophila, aeromonas sobira, Aeromonas veronii and tilapia streptococcus, and tilapia feed containing the compound Chinese herb preparation. The preparation can significantly improve the resistance of tilapia to streptococcus agalactiae and can also effectively increase the survival rate of tilapia, wherein the control rate of the preparation on streptococcus agalactiae ranges from 52% to 85%. The compound Chinese herb preparation also has good bacteriostatic activity on aeromonas hydrophila, aeromonas sobira and Aeromonas veronii which are common in tilapia. The feed containing the compound Chinese herb preparation is safe, nontoxic, simple in preparing process and capable of being directly added into commercial feed.