Abstract: Engineering properties of deep clay in H uanghuai area,such as dens ity,water content,particle size, mineralogical compos ition,expansibility,compressibility and shear strength etc., are summarized. It shows that the deep clay in H uanghuai area is s aturated expans ive soil with high liquid limit. The index properties increas e or decrease regularly with the depth or the relative water content,ex cept that they usually os cillate locally. Triaxial compression test with the remolded deep clay shows that its fraction angle is lower than that of the common shallow clay, and the strength envelope deflects with high confining stress.