Sand solidification technology is widely applied in engineering. This paper presents experimental methods to analyze the effect of adding urea to a culture medium for sand solidification. The results show that adding urea to the culture medium increases urease activity and inhibits bacterial growth, and the optimal amount of added urea is between 5 and $20\mathrm{g}/\mathrm{L}$ . Adding urea after sterilization markedly increases the strength of the injecting path for sand column solidification. However, a long injecting path leads to differences in strength between the entrance section and middle section, resulting in lower overall strength. The faster the injection speed, the higher is the overall strength of the sand columns. When $20\mathrm{g}/\mathrm{L}$ of urea is added, the overall strengths of the solidified sand columns increase with larger sand particle size. Adding different amounts of urea is suitable for the solidification of corresponding sand column sizes. Therefore, adding urea to the culture medium for sand solidification is significant for various sand particle sizes. The results will act as a guide for the application of sand solidification technology.