A device for simultaneously measuring mercury, cadmium, zinc, and lead, comprising: a gas generating device, wherein the gas generating device comprises an air generator and a nitrogen/hydrogen generator so as to be switchable between an air atmosphere and a nitrogen/hydrogen; a quartz analysis tube connected to the gas generating device; wherein the quartz analysis tube comprises a sample heating zone, a high-temperature packing zone and a quartz collimating tube arranged in a listed sequence, wherein the high-temperature packing zone is filled with magnesium oxide, calcium oxide or kaolin particles so as to absorb cadmium, lead, zinc and other elements partially carried in the combustion flue gas, and the quartz collimating tube is configured to aggregate the analytes released from the sample heating zone and the high-temperature packing zone into a beam; an atomic absorption detection device arranged behind the quartz analysis tube; wherein the atomic absorption detection device comprises a first atomic absorption detector, a flame device, and a light source, wherein the first atomic absorption detector is scanning optical fiber spectrometer, and the light source is a lamp with composite elements of the cadmium, zinc and lead elements; a quartz catalytic tube arranged behind the atomic absorption detection device; wherein the quartz catalytic tube comprises a flame buffer zone and an adsorption packing zone arranged in sequence, wherein the adsorption packing zone is packed with oxide particles of calcium oxide and manganese dioxide to absorb acid gas and nitrogen oxides generated during a combustion process; and an atomic absorption mercury measuring device arranged behind the quartz catalytic tube; wherein the atomic absorption mercury measuring device comprises a mercury enrichment tube, a second atomic absorption detector and an air pump arranged in a listed sequence. a gas generating device, wherein the gas generating device comprises an air generator and a nitrogen/hydrogen generator so as to be switchable between an air atmosphere and a nitrogen/hydrogen; a quartz analysis tube connected to the gas generating device; wherein the quartz analysis tube comprises a sample heating zone, a high-temperature packing zone and a quartz collimating tube arranged in a listed sequence, wherein the high-temperature packing zone is filled with magnesium oxide, calcium oxide or kaolin particles so as to absorb cadmium, lead, zinc and other elements partially carried in the combustion flue gas, and the quartz collimating tube is configured to aggregate the analytes released from the sample heating zone and the high-temperature packing zone into a beam; an atomic absorption detection device arranged behind the quartz analysis tube; wherein the atomic absorption detection device comprises a first atomic absorption detector, a flame device, and a light source, wherein the first atomic absorption detector is scanning optical fiber spectrometer, and the light source is a lamp with composite elements of the cadmium, zinc and lead elements; a quartz catalytic tube arranged behind the atomic absorption detection device; wherein the quartz catalytic tube comprises a flame buffer zone and an adsorption packing zone arranged in sequence, wherein the adsorption packing zone is packed with oxide particles of calcium oxide and manganese dioxide to absorb acid gas and nitrogen oxides generated during a combustion process; and an atomic absorption mercury measuring device arranged behind the quartz catalytic tube; wherein the atomic absorption mercury measuring device comprises a mercury enrichment tube, a second atomic absorption detector and an air pump arranged in a listed sequence.