The invention relates to the related technical field of 
pollution source monitoring, in particular to a fixed 
pollution source VOCs online sampling, calibration and pretreatment 
system which comprises a sampling unit, a calibration device and a pretreatment 
system, and the sampling unit comprises a gas collection channel, a filter 
assembly, a mounting head, a pipeline connector and a heating structure. The gas collection channel is of a tubular structure; a 
pollution source VOCs online sampling, calibration and pretreatment 
system composed of a sampling unit, a calibration device and a pretreatment system is arranged, and the sampling unit is composed of a gas collection channel, a filter 
assembly, a mounting head, a pipeline connector and a heating structure. Therefore, the gas flowing into the gas collection channel is preheated through the heating structure, so that the sample gas is always kept in a constant high-temperature state, the loss of the sample gas caused by adsorption, condensation and the like is prevented, and the purpose of improving the sample detection accuracy is achieved.