A solid-phase microextraction （SPME） tube with large-capacity was developed and an on-site SPME sampling device was constructed to realize on-site sampling of trace pollutants in environmental water. Phthalates and polycyclic aromatic hydrocarbons （PAHs） were used to evaluate the performance of the SPME tubes and the on-site SPME device with gas chromatography-hydrogen flame ionization detector. The results showed that the extraction tube had stable performance and good reproducibility， and the extraction amount of a single extraction tube was 13-31 times that of a needle extraction head. The sampling device is flexible to be assembled and easy to be carried. The limit of detection of the on-site SPME method established with a sampling device of three extraction tubes was 0.01-0.04 ng/L for four types of PAHs in water. The sensitivity of the on-site SPME was 6-14 times higher than that of a single extraction tube and 36-53 times higher than that of a needle extraction head. The rate of recovery at different spiked levels was 92.0% to 115.7%， with a relative standard deviation of 1.5% to 13.1%. It is indicated that the constructed device has strong enrichment capacity， flexible assembly， and can be automated and used for efficient monitoring of different pollutants in environmental water.