A solenoid valve, comprising a first pipe, an electromagnetic mechanism to control open-on and cut-off of the first pipe, and a pressure relief mechanism in communication with the first pipe; wherein the pressure relief mechanism comprises a first mounting base with a first cavity, a second pipe in communication with the first cavity and the first pipe, respectively, an outlet opening in communication with the first cavity, and an overflow opening in communication with the first cavity and located above the outlet opening, further wherein an communicating opening between the second pipe and the first cavity is located below the outlet opening; the pressure relief mechanism further comprises a first movable mechanism disposed in the first cavity in a manner of being movable up and down for blocking or communicating the communicating opening and the outlet opening, and a second movable mechanism disposed in the first movable mechanism in a manner of being movable up and down for blocking or communicating the communicating opening and the overflow opening; is characterized in that, the communicating opening is located at the bottom of the first cavity, and the pressure relief mechanism further comprises a sealing mechanism located above the second pipe and covering the communicating opening in a manner of being movable up and down, wherein the sealing mechanism comprises: a sealing plate covering the communicating opening, which is capable of being sucked onto the communicating opening when a negative pressure occurs in the second pipe, and a guide column disposed below the sealing plate; wherein a through hole through which the guide column passes is provided in the first mounting base, and a stop block for preventing the guide column from emerging from the through hole upward is provided on a lower end portion of the guide column. wherein the pressure relief mechanism comprises a first mounting base with a first cavity, a second pipe in communication with the first cavity and the first pipe, respectively, an outlet opening in communication with the first cavity, and an overflow opening in communication with the first cavity and located above the outlet opening, further wherein an communicating opening between the second pipe and the first cavity is located below the outlet opening; the pressure relief mechanism further comprises a first movable mechanism disposed in the first cavity in a manner of being movable up and down for blocking or communicating the communicating opening and the outlet opening, and a second movable mechanism disposed in the first movable mechanism in a manner of being movable up and down for blocking or communicating the communicating opening and the overflow opening; is characterized in that, the communicating opening is located at the bottom of the first cavity, and the pressure relief mechanism further comprises a sealing mechanism located above the second pipe and covering the communicating opening in a manner of being movable up and down, wherein the sealing mechanism comprises: a sealing plate covering the communicating opening, which is capable of being sucked onto the communicating opening when a negative pressure occurs in the second pipe, and a guide column disposed below the sealing plate; wherein a through hole through which the guide column passes is provided in the first mounting base, and a stop block for preventing the guide column from emerging from the through hole upward is provided on a lower end portion of the guide column. a sealing plate covering the communicating opening, which is capable of being sucked onto the communicating opening when a negative pressure occurs in the second pipe, and a guide column disposed below the sealing plate; wherein a through hole through which the guide column passes is provided in the first mounting base, and a stop block for preventing the guide column from emerging from the through hole upward is provided on a lower end portion of the guide column.