Abstract: Changchun is underlain by Cretaceous mudstone,belong to the extreme soft rock or soft rock,has the characteristics of softening and disintegration.At present,some construction projects need to use Changchun deep mudstone as pile foundation bearing layer.This kind of rock,national standard "Code for Investigation of Geotechnical Engineering" cannot think of the weathering degree of division,this view is contrary to Changchun engineering construction and engineering experience.Jilin landmark "Geotechnical Engineering Investigation Technology Interim Provisions" of the standard penetration test of mudstone weathered state,gives the whole weathered to medium weathering mudstone criteria,but the influence factors of the standard penetration test is many,so this method is not suitable for deep mudstone.This paper uses the method of shear wave velocity test,proposes the division standard of weathering degree of the Changchun mudstone,especially solves the deep mudstone weathering degree division problems.By the engineering test,the effect is good.