Abstract: Based on a large ground engineering of tanks in the alluvial plain of Yellow River, this paper illustrates a succeeded practice of reinforcing soft soil ground. The soil, which comprises silt in shallow layer and fine sand or silt in deep layer in study area, has a low bearing capacity and a relatively high compressibility. For the mechanical properties of this soft soil, deep mixing pile is used to reinforce its ground. Small strain DET, disclosure of piles and in-situ loading tests are conducted respectively when the piles formed. The results of tests show that bearing capacity rises rapidly, uneven subsidence and a bigger absolute subsidence don't appear still. The results also indicate that the 800 piles in the area all meet the design specification. The measures and principles followed in the processing of construction are accentuated by the authors to qualify the deep mixing piles.