Abstract: The deformation and long-term deformation of soft soils are concerned both in academic and engineering fields, and they lead to the excessive settlement and post-construction settlement of soft layers. Based on one-dimensional consolidation principle, the tests on the constant stress ratio consolidation with K₀, which is more actual consolidation state of soft foundation, are carried out to study the primary and secondary consolidation characteristics. The undisturbed samples used are obtained from a dredger fill foundation in Shantou of Guangdong province. By comparing with the K₀ confined compression tests, it is noted that the instantaneous compression is significant in the tests on the constant stress ratio consolidation with K₀, which affect the primary and secondary deformations. There are higher compression index, lower compression modulus and lower secondary consolidation coefficient than those in K₀ confined compression tests, and the duration of the primary consolidation is shorter.