Nowadays, agricultural practices cause serious problem for soil environment, especially in the long-term intensive agriculture system. Soil quality assessment using physicochemical method has many' disadvantages. On the other hand, soil quality assessment using biological method offers several advantages, i.e. it provides accurate results at the sampling time and can predict long-term effects of pollution on the growth of living organisms in the soil. This study used nematodes as bioindicator to assess the quality of pepper cultivation area in Loc Hung commune at six sampling points, sampling notations were LH1, LH2, LH3, LH4, LH5 and LH6. A total of 35 genera belonging to 21 families and 8 orders were recorded. By analysing the community structure and calculating the biological diversity index (the Margalef index (d), the maturity index (MI), cp value and establishing ecological triangle model), our study showed that the soil quality in this studied area is relatively stable and does not suffer any significant contamination.