Abstract: Metallothionein ( MT) is a kind of multifunctional inducible protein widely distributed in the organism, with the functions of transportation and storage of metal ions, scavenging free radicals function, activation ( inactivation) function of zinc regulatory proteins, and has been one of the hot fields of biology and medicine in basic research and applied research in recent years.In this paper, the fermentation conditions of a strain of high yield recombinant Bacillus subtilis strain were optimized.Through the single factor experiment, the optimal conditions for the growth of recombinant Bacillus subtilis as follows, temperature 37 ℃, initial p H7, rotation speed 220 r/min, inoculation amount 4%, and the optimal fermentation conditions of induction as follows, OD₆₀₀= 3.9, IPTG concentration 1 mmol/L, the rotate speed 220 r/min, the induction time 48 h, 50 μmol/L Cd²⁺, MgSO₄ ( 1%) , sucrose ( 2%) , nitrogen source ( 1.5% yeast extract + peptone + ammonium chloride) ( 2 ∶ 2 ∶ 1) , the expression of MT reached 0.135 mg/m L.This study provides some theoretical basis for the development of the natural, efficient marine source metallothionein.