The field experimentation to test the appropriate density for the D2101 soybean variety was conducted in two growing seasons, Summer-Autumn 2010 and the Spring 2011 in Muong Khuong district, Lao Cai province. The results obtained from the experimentation show that the crop density is a key influential factor on the yield of the D2101 soybean variety. With the variation of the crop density from 25-50 plants/m2, the duration of the D2101 soybean variety does not change very much, however, the height and resistant capacity of the soybean have changed significantly. The resistant capacity to plant falling of soybean in the density from 25-30 plants/m2 is much better than that of the soybean in the density from 42-50 plants/m2. The density from 25-30 plants/m2 is the most appropriate for the D2101 soybean variety in Muong Khuong district, Lao Cai province with the yield obtained from 18.4 -20.4 quintals/ha (in Summer-Autumn 2010 growing season) and 25.9-28.8 quintals/ha (in Spring 2011).