Abstract: Study on solid formulation of Hrp^- mutant was explored. The preparation method of Hrp^- mutant solid formulation was worked out through screening various carriers, protection agents and antibacterial agents. The preparation process was evaluated in this paper. At first, bacterial cultures after fermentation were collected by centrifugation at 5000 r/min for 10 min, washed twice in sterile water and then suspended in mineral oil, followed by shaking evenly for 15—20 min. After that, the solid formulation was prepared by mixing the suspension with sterilized peat with the proportion of 1:1. Finally, nisin and natamycin were added into the mixture to inhibit other miscellaneous microbes. The prepared solid agent survived for 6 months under the temperature of 25 ℃, pH 5.3, water content of 35% and without vacuum. The survival rate could sustain at 44.4%, and the biomass reached 1.12×10¹⁰cfu/g.