Tight sandstone gas reservoirs, characterized by low permeability and small pore throats, often encounter water blocking damage during development, which impacts gas well productivity. In this study, we conducted core imbibition experiments and combined them with nuclear magnetic resonance technology to compare and analyze the effects of two types of water-blocking agents and explore their mechanisms in micro-nano-scale pores. The results show that both types of water-blocking agents effectively reduce water permeability. Those containing fluorinated surfactants exhibit both hydrophobic and oleophobic properties, effectively mitigating damage caused by water accumulation, resulting in superior water-blocking effects. With the increasing imbibition time, the core imbibition mass increases, and water blocking damage is caused by water occupying smaller pores. The water-blocking agents inhibit the imbibition of small pores, thereby reducing water blocking damage. The optimal water-blocking effect is achieved with a 35% concentration of water-blocking agent, an injection volume of 8 pore volumes (PV), and a soaking time of 24 h. These findings provide crucial theoretical support for the design of water-blocking construction processes in the Sulige Gas Field.