Seeds of .Arabidopsis. were planted separately in the medium of different nutrient element deficiency of N, P, K, Ca, Mg, Fe and Sucrose, in the condition of 22 ℃ long-day (16 h light / 8 h dark) 10 days. The .Arabidopsis. seedings had the corresponding phenotype. Histochemical assay of .GUS. activity and Q-PCR were used to analyze and examine the expression of the 4.CL1, 4CL2. and 4.CL3. gene. The research results have showed that the potassium (K) can induct the expression of the 4.CL. gene involved in the synthesis pathway of the lignin and flavonoid.