A stretching and sealing device for a blow molding machine, comprising a machine frame (1), a guide rail (2) disposed on the machine frame (1), a stretching mechanism, and a sealing mechanism. The stretching mechanism comprises a first sliding block (3) movably disposed on the guide rail (2), a pull rod (4) disposed on the first sliding block (3), and an actuating cylinder (5) disposed on the machine frame (1) and used for driving the first sliding block (3). The sealing mechanism comprises a second sliding block (6) and a third sliding block (7) which are movably disposed on the guide rail (2), the second sliding block (6) being located over the first sliding block (3), and the third sliding block (7) being provided below the first sliding block (3). The sealing mechanism further comprises a connecting rod (8) connected between the second sliding block (6) and the third sliding block (7), and a sealing cylinder (9) disposed on the third sliding block (7). The pull rod (4) is inserted into the sealing cylinder (9). The device implements the mechanical linkage of the stretching mechanism and the sealing mechanism so as to improve the precision of high-speed stretching and sealing actions of the blow molding machine, thereby improving the operation stability and the production efficiency of the blow molding machine. When blowing molding a bottle, the additional power source is not required to be provided for a sealing component, thereby reducing the device cost and the production cost.