Abstract: A series of tests have been carried out for loess in saturated and natural conditions respectively using a portable dynamic penetrometer with variable energy. Coupled with the apparatus, the static load tests were also performed on loess in same conditions. On the basis of the results obtained, the geotechnical properties of loess, especially its collapsibility are analyzed. Compared to other methods measuring the collapsibility index of loess, the authors proposed an indirect and simple method to evaluate the collapsibility of loess by measuring the mechanical resistance in situ with the penetrometer.