The related integrated on-line gas detector can continual detect the content of CO, CO2, SO2, NO, NO2, N2O, CH4, HCl, H2S, HF, O2, H2 and Cl2 in smoke gas, kiln gas and furnace gas, which comprises: a sampling probe, a back-blow valve, a pump, a dehydrator, a fine filter, a bypass valve, a check valve, a stable valve, a flowmeter, a gas analysis sensor, a controller, a signal display, a signal output interface, an operation button, a drier, a power, an outdoor case, a sampling pipe, a sample-gas pipe, and a back-blow pipe. This invention has wide application.