A low-temperature gas generating agent comprises the following components in percentage by mass: 40 to 60% of guanidine nitrate, 25 to 55% of a combustion temperature regulator, 3 to 15% of a combustion rate regulator and 0.5 to 3% of a binder. The combustion temperature regulator can be oxamide, ammonium oxalate, ammonium sulfate, Oxalic dihydrazide and azodicarbonamide; the combustion rate regulator can be bistetrazole ammonium salt, zinc oxide and a copper and iron oxide, and the binder can be clay, paraffin and modified cellulose. The low-temperature gas generating agent has the characteristics of low combustion temperature, fast combustion rate, low solid residue content, and the like, and can meet the requirement of rapid inflating of a sealed capsule.