Abstract: According to many projects of Sichuan, Tibet, and so on, there are engineering geological problems of deep overburden with depth of dozens meters even hundred meters in most southwest valley. During construction, the study of compression feature which is limited of depth of overburden is often based on borehole samples in earlier stage, mainly including testing in borehole and laboratory test of borehole sample. Because of disturbance and stress change of borehole sample, there is influence to testing result. In this article, the main composition of riverbed substance is generally classified firstly, then the typical projects is chosen, and the sample of foundation pit is reviewed during excavation, the difference between borehole sample and the sample of foundation pit is compared, and the reasons of generation difference of partial parameters are analyzed.