At present, the research on the consolidation deformation of soft soil under unloading mainly focuses on the instantaneous unloading. In order to clarify the evolution of consolidation deformation of soft soil under linear unloading, through the one-dimensional consolidation theory of Terzaghi and the principle of effective stress, an effective method is proposed to study the general solution of the soft soil foundation under the arbitrary unloading rate and solve the analytical solution of the consolidation equation under linear unloading. The results show that: (1) the negative excess pore pressure generated in soft soil foundation under linear unloading can be divided into three stages: growth period, rapid dissipation period and slow dissipation period; (2) unloading rate affects the growth path and dissipation rate of negative excess pore pressure; and (3) unloading affects the maximum negative excess pore pressure with the unloading amount approximately linearly increasing. Finally, taking engineering examples for comparative analysis, it is found that the negative excess pore pressure and its dissipation rate induced by unloading are the highest at the end of unloading. The theoretical results with evolution trends are in good agreement with field measurements.