A gas mixing device, comprising: a housing, which is provided with an air inlet, a combustion gas inlet, and an EGR exhaust gas inlet; a first mixing core arranged in the housing, wherein the air inlet and the combustion gas inlet respectively communicate with the first mixing core to form a mixed gas in the first mixing core; a first measurement assembly, which is connected on the first mixing core and which is configured to provide measurement data in order to obtain a first flow rate of the mixed gas; a second mixing core arranged in the housing, wherein the EGR exhaust gas inlet and the first mixing core respectively communicate with the second mixing core; a second measurement assembly, which is connected on the EGR exhaust gas inlet and which is configured to provide measurement data in order to obtain a second flow rate of an EGR exhaust gas; and a throat body disposed in the housing between the first mixing core and the second mixing core, the throat body comprising a depressurization section and a first smooth section connected to the depressurization section; wherein the second mixing core comprises a guide section having a diameter larger than that of the first smooth section, and a first passage is formed between the guide section and the first smooth section, and EGR exhaust gas from the EGR exhaust gas inlet enters the first passage to mix with the mixed gas from the first smooth section of throat body; and a second passage is formed between the first mixing core and the housing, the second passage is in communication with the combustion gas inlet, and the first mixing core is provided with a first injection port. a housing, which is provided with an air inlet, a combustion gas inlet, and an EGR exhaust gas inlet; a first mixing core arranged in the housing, wherein the air inlet and the combustion gas inlet respectively communicate with the first mixing core to form a mixed gas in the first mixing core; a first measurement assembly, which is connected on the first mixing core and which is configured to provide measurement data in order to obtain a first flow rate of the mixed gas; a second mixing core arranged in the housing, wherein the EGR exhaust gas inlet and the first mixing core respectively communicate with the second mixing core; a second measurement assembly, which is connected on the EGR exhaust gas inlet and which is configured to provide measurement data in order to obtain a second flow rate of an EGR exhaust gas; and a throat body disposed in the housing between the first mixing core and the second mixing core, the throat body comprising a depressurization section and a first smooth section connected to the depressurization section; wherein the second mixing core comprises a guide section having a diameter larger than that of the first smooth section, and a first passage is formed between the guide section and the first smooth section, and EGR exhaust gas from the EGR exhaust gas inlet enters the first passage to mix with the mixed gas from the first smooth section of throat body; and a second passage is formed between the first mixing core and the housing, the second passage is in communication with the combustion gas inlet, and the first mixing core is provided with a first injection port.