A study on the compressibility of high-water-content mud treated by the physicochemical composite method under different initial conditions was conducted through one-dimensional compression tests. The effects of the total duration of step loading, curing time, dosage of solidifying agent, and dosage of flocculant on the compression curve, compression index, and yield stress of the mud were investigated. The concept of the intrinsic compression curve was introduced to normalize the compression data, enabling further analysis of the compressibility of the mud under different initial conditions. The results show that the compression curve of the mud treated by the physicochemical composite method exhibits a distinct two-stage characteristic, with the post-yield compression index being approximately 20 times that of the pre-yield compression index. The yield stress of the mud increases linearly with the increase in solidifying agent dosage and the decrease in the total duration of step loading. The yield stress of the mud follows a logarithmic growth pattern with prolonged curing time. There exists an optimal dosage of flocculant that maximizes dewatering efficiency and enhances structural strength.