The rheological parameters of foamed lightweight soil with different density grades were measured by Brinell viscometer,and the effect of foamed lightweight soil on rheological behavior was studied.The results show that the rheological behavior of foamed lightweight soil is also consistent with Bingham fluid characteristics.The introduc-tion of foam mainly affects the apparent viscosity of slurry at low shear speed.With the increase of foam content,the yield stress of slurry increases obviously,while the plastic viscosity decreases at first and then slows down.The plastic viscosity is closely related to the fluidity of the foamed lightweight soil,which can be used to evaluate the workability of the newly mixed foamed lightweight soil.