Abstract: Dimensional analysis can aid the design of experiments and expression of conciseness of the results generated by them.The dimensionless groups, which are the output of a successful dimensional analysis, are usually developed.This paper takes the ground bearing strength test as the example, shows the Buckingham's π theorem and improves the calculating methods of amelioration by Butterfield.The author studied the model experiment of siphon drainage technology on the bank slope by numerical simulation and validated the results of dimensional analysis, and proposed suggestions for the model experiment essential parameter selection.