[Objective] To reveal the effect of wood vinegar concentration on soil enzymatic activities in order to determine the optimal application concentration of wood vinegar in low and medium fertility soils in Northwest Liaoning Province.[Methods] Pot experiments were conducted, and wood vinegar with different concentrations (0.10%, 0.15% and 0.30%) were selected. The agronomic indexes of pot grown pakchoi were determined and the soil enzyme activities were measured to evaluate the soil fertility quality.[Results] Wood vinegar significantly improved the stem diameter and the root length of pakchoi, and consequently increased the yield of pakchoi. Wood vinegar with 0.30% concentration showed the best effect in low fertility soil while wood vinegar with 0.15% concentration showed the best effect in medium fertility soil, and the fresh weight of pakchoi was increased by 57.78% and 46.06%, respectively, compared with the control. Wood vinegar also significantly enhanced the activities of soil amylase, urease, protease, phosphatase, catalase and dehydrogenase. Biological index of fertility and enzymatic activity number were the highest, in low fertility soil with 0.30% concentration of wood vinegar and in medium fertility soil with 0.15% concentration of wood vinegar.[Conclusion] Wood vinegar can be used as a good soil amendment to improve soil fertility and increase vegetable yield in Northwest Liaoning Province.