A fast sampler of trace polycyclic aromatic hydrocarbons in water based on an electro spinning nano fiber membrane is disclosed. The invention relates to a water quality monitoring device, provides an adsorption sampler of polycyclic aromatic hydrocarbon based on an electro spinning lactic acid-caprolactone nano fiber membrane. In the sampler, a water collection sleeve is fixed with a membrane supporting sleeve, a check valve is arranged at the lower part of the water collection sleeve and is connected with a sampling needle and the membrane supporting sleeve, the water collection sleeve can be externally connected with a polytetrafluoroethylene sampling tube to discharge water, the outer wall of the membrane supporting sleeve is used for fixing the fiber membrane to adsorb the polycyclic aromatic hydrocarbon in the water, a water diversion bin is arranged at the bottom of the membrane supporting sleeve, the bottom of the membrane supporting sleeve is connected with the check valve, and a pulling piston is used for sucking a water sample and transports the water sample to the water collection sleeve to be contacted with the fiber membrane. The electro spinning lactic acid-caprolactone nano fiber membrane for matching is prepared through a high-voltage electrostatic spinning method. The sampler has the advantages that sampling, adsorption enrichment and solvent desorption are synchronously carried out, and easy to control, water samples before and after enrichment are respectively stored without mutual interference, the manual operation is adopted without matching equipment; the adsorption ability of the fiber membrane is strong, and the selectivity of different pollutants can be realized by changing different fiber membranes, the structure is simple and the operation is convenient, and the fiber membrane is easy to disassemble.