A dual-stage hybrid inflator, comprising: a main casing comprising a bottom housing and an upper housing, the upper housing fixed at a top of the bottom housing relatively and the upper housing together with the bottom housing to form a complete sealed casing, a bottom wall of the bottom housing disposed with a first ignition hole and a second ignition hole, and a top wall of the upper housing disposed with a through hole; a central pipe being a hollow pipe, a bottom of the central pipe fixed onto the bottom housing relatively, a top of the central pipe penetrating the through hole relatively to fix with the upper housing, and a pipe wall of the central pipe having a plurality of convective holes; a disc set disposed at the top of the central pipe relatively to prevent gas escaping from the main casing, and separated from the top of the central pipe when an inner side of the disc set is pushed with a certain degree of force; a first propellant chamber assembly comprising a cushion ring and a first cup cover, wherein the cushion ring is disposed at an internal circular wall of the bottom housing relatively; a center of the first cup cover is disposed with a sheath opening sheathed on the central pipe relatively, the first cup cover is disposed at a top of the cushion ring so as to form a first propellant chamber with the bottom housing, and the first propellant chamber is disposed with a propellant having a first dosage; a second propellant chamber assembly disposed at the bottom housing and comprising a cup body of a second propellant chamber and a second cup cover, wherein the cup body of the second propellant chamber has a through hole fixed with the second ignition hole relatively, the cup body of the second propellant chamber is filled with a propellant having a second dosage, and the second cup cover has a shape relative to a shape of the cup body of the second propellant chamber and covers the cup body of the second propellant chamber; a first igniter assembly penetrating through the first ignition hole to be disposed in the first propellant chamber, for producing a first ignition airflow after receiving a first ignition signal, so as to trigger the propellant having the first dosage to burn; a second igniter assembly penetrating through the second ignition hole and the through hole to be disposed in the cup body of the second propellant chamber, for producing a second ignition airflow after receiving a second ignition signal, so as to trigger the propellant having the second dosage to burn; and an exhaust hood sheathed and fixed on the main casing relatively, and a deposition space formed between the exhaust hood and the main casing for accommodating a solid residue produced after burning, and the exhaust hood having a plurality of exhaust holes for exhausting gas. a main casing comprising a bottom housing and an upper housing, the upper housing fixed at a top of the bottom housing relatively and the upper housing together with the bottom housing to form a complete sealed casing, a bottom wall of the bottom housing disposed with a first ignition hole and a second ignition hole, and a top wall of the upper housing disposed with a through hole; a central pipe being a hollow pipe, a bottom of the central pipe fixed onto the bottom housing relatively, a top of the central pipe penetrating the through hole relatively to fix with the upper housing, and a pipe wall of the central pipe having a plurality of convective holes; a disc set disposed at the top of the central pipe relatively to prevent gas escaping from the main casing, and separated from the top of the central pipe when an inner side of the disc set is pushed with a certain degree of force; a first propellant chamber assembly comprising a cushion ring and a first cup cover, wherein the cushion ring is disposed at an internal circular wall of the bottom housing relatively; a center of the first cup cover is disposed with a sheath opening sheathed on the central pipe relatively, the first cup cover is disposed at a top of the cushion ring so as to form a first propellant chamber with the bottom housing, and the first propellant chamber is disposed with a propellant having a first dosage; a second propellant chamber assembly disposed at the bottom housing and comprising a cup body of a second propellant chamber and a second cup cover, wherein the cup body of the second propellant chamber has a through hole fixed with the second ignition hole relatively, the cup body of the second propellant chamber is filled with a propellant having a second dosage, and the second cup cover has a shape relative to a shape of the cup body of the second propellant chamber and covers the cup body of the second propellant chamber; a first igniter assembly penetrating through the first ignition hole to be disposed in the first propellant chamber, for producing a first ignition airflow after receiving a first ignition signal, so as to trigger the propellant having the first dosage to burn; a second igniter assembly penetrating through the second ignition hole and the through hole to be disposed in the cup body of the second propellant chamber, for producing a second ignition airflow after receiving a second ignition signal, so as to trigger the propellant having the second dosage to burn; and an exhaust hood sheathed and fixed on the main casing relatively, and a deposition space formed between the exhaust hood and the main casing for accommodating a solid residue produced after burning, and the exhaust hood having a plurality of exhaust holes for exhausting gas.