In the construction of large chambers and chamber groups in coal mines in the western region of China, there are common difficulties such as unclear deformation laws of surrounding rock in chambers and great difficulty in support, which has become one of the main factors restricting the safe construction of large chambers in coal mines. Based on the construction project of bottom loading chambers in the Hongqingliang Coal Mine in Ordos, a three-dimensional computational model of the chamber was established using FLAC^3D to simulate the stability and long-term stability of the chamber after one-time support excavation. It was found that the deformation of the surrounding rock is significant in the upper roof of the chamber and at the connection between the chamber and the inclined shaft; the thickness of the plastic zone in the two sides area is about 6 m, the thickness of the plastic zone in the roof is about 5 m, and the thickness of the plastic zone in the bottom is about 5.5 m. Strengthening of anchor support is required, with recommended anchor lengths of 7.5 to 8 m. Engineering measurements showed that after excavation and support of the chamber, the stress on the anchor rods and cables increased rapidly in the initial stage and gradually stabilized in the later stage. The stable deformation time of the internal anchor rods and cables in the chamber is approximately 20 days, and the stable zone of stress concentration at the connection between the chamber and the inclined shaft is approximately 15 days. The measured stress on the anchor rods and cables is less than the breaking load, indicating that the overall support structure of the chamber is stable and safe. The research results will provide data reference and theoretical support for the construction of similar large chambers in soft rock formations in the western region.