A experiment of 12 000 kNm energy dynamic compaction for collapsible loess was carried out. Through comprehensive analyzing the data of standard penetration test,soil mechanics experiment,cone penetration test,Rayleigh test,static test,and compare with other energy dynamic compaction results of collapsible loess,some results of effective reinforced depth and coefficient of collapsibility were obtained. References for design,construction,and detection of collapsible loess were provided.