The uptake of water by deep coal rock has a significant impact on gas production. However, the extent of this impact is controlled by factors such as the micro-pores and macro-structure of the coal rock, making it difficult to determine the variation patterns. In order to understand the characteristics of water absorption in deep coal rock and its effects on gas production, experiments were conducted using a spontaneous imbibition apparatus and a sensitivity evaluation device. The results obtained shed light on the water absorption characteristics of deep coal rock and discussed its influence on gas production. The findings are as follows: (1) During water absorption, deep coal rock exhibits an initial increase followed by a decrease in trend, while oil absorption shows an overall increasing trend. With the increase in water absorption, the interaction between fracturing fluid and coal rock leads to fracture opening. Despite no change in mass, the increased buoyancy of coal rock in liquid is reflected in a downward trend in measured mass. (2) The addition of KCl solution for testing after water absorption exhibits a stable increase in mass. Similarly, the addition of NaCl solution shows a pattern consistent with the distilled water system. (3) A significant amount of liquid remains trapped in cleavages and fractures, with negligible negative effects observed in the initial stages. With an increase in water saturation, the overall sensitivity of coal rock permeability becomes stronger. This study provides valuable insights for the design of hydraulic fracturing in deep coal rock and gas production.