The recombinant Corynebacterium glutamicum R102δmetX(R102 with deletion in the metX gene) was constructed.Fractional factorial design was used to evaluate the effects of medium components on the production of threonine.Glucose,yeast extract and enzymatic casein were the most important factors among twelve tested variables that influence the production of threonine.Based on the experimental results,the path of steepest ascent was undertaken to approach the optimal region of these factors.Central composite design and response surface analysis were subsequently employed for further optimization.The optimal medium for threonine synthesis was composed of;glucose 50.78g/L,yeast extract 6 g/L,enzymatic casein 0.99 g/L,biotin 80μg /L,VB1 2mg/L,CaCO3 20g/L,(NH4)2SO4 15.15 g/L,MgSO4·7H2O 0.5 g/L,KH2PO4 0.5 g/L,K2HPO4 0.5 g/L,FeSO4·7H2O 0.02 g/L,MnSO4·7H2O 0.02g/L,inoculation quantity 8%.Under the optimum conditions,the threonine yield of the recombinant strain was 3.35g/L,which was 30% higher than the original medium components.