To investigate the compressive deformation characteristics of saline soil under dissolution, taking sulfite saline soil from a certain area in Xinjiang as the research object, using laboratory seepage dissolution tests, compression tests, and micro-morphological analysis, the influence of dissolution on the compressive properties of sulfite saline soil was analyzed, and the deformation degradation mechanism of saline soil under seepage dissolution effects was revealed. The results show that under dissolution, the surface porosity of the specimen increases with the salt content, and the electrical conductivity of the leachate decreases rapidly initially and then gradually stabilizes with dissolution time. Dissolution significantly increases the compression coefficient of the specimen, which increases linearly with the salt content. Under dissolution, aggregates disintegrate, large flaky particles are transformed into medium and small particles with rounded shapes, and inter-particle pores and interlocked pores are converted into crystalline dissolution pores, thereby leading to more significant macroscopic deformation.