<p>In this paper, the damage mechanism of sandstone under the action of water and force is clarified by analyzing different creep stages of rock, and the corresponding damage variables are put forward. The effects of accelerated creep and initial water content on the model are fully considered by improving the Model. Based on the relationship between model parameters and initial water content as well as between model parameters and stress, a new method for determining creep parameters is proposed, and a relatively perfect nonlinear creep constitutive model of rock under the action of water and force is established. Taking sandstone as the research object, data were obtained through uniaxial creep tests under different initial water contents, and verification was conducted combined with FLAC 3D numerical simulation. Compared with the experimental results and numerical results, the model established in this paper can better reflect the deterioration characteristics of sandstone under water–rock coupling. Finally, the damage characteristics of rock with variable water content are briefly analyzed, and the superiority of the nonlinear creep constitutive model of rock with variable water content under the action of water and force is proposed. The results show that the model can well reflect the deterioration characteristics of sandstone under water–rock coupling.</p>