Abstract: Using small scale model rig, a comparative experimental study was conducted to investigate process control and quality control in the deep soil mixing (DSM) method and contra-rotational shear deep soil mixing (CS-DSM) method. Research emphasis was placed on the effects of cement content, blade rotation number T on the uniformity and unconfined compression strength UCS of mixing pile. A notably improved uniformity and continuity of the CS-DSM piles over the DSM piles is confirmed by the experimental results. The strength ratio Rs ranges from 1.41 to 6.4, this ratio shows an exponential decrease with increasing T. Furthermore, the results from 24 model piles provide insights into the fundamental relationship and distinctions between UCS and T. Leveraging this discovery, construction parameters can be optimized to ensure the target design strength for both types of piles. The model test results clearly demonstrate the differences in construction quality between the DSM method and the CS-DSM method. The technical basis established in this study serves as a cornerstone for process control and quality assurance in installing high quality CS-DSM piles.