In order to realize on-site sampling of trace pollutants in environmental water, a large-capacity solid-phase microextraction (SPME) tube was developed, and an on-site SPME sampling device was constructed. The performance of the SPME tube and the on-site SPME device was evaluated using gas chromatography-flame ionization detector for the analysis of phthalates and polycyclic aromatic hydrocarbons (PAHs). Results show that the extraction performance of the tube is stable and reproducible, and the sampling device is flexible to be assembled and easy to carry. The detection limits obtained by the on-site SPME device with 3 SPME tubes were 0.01~0.04 ng/L, which were 6~14 times higher than that of a single SPME tube, and 36~53 times higher than that of the SPME fiber. The recoveries were 92.0%~115.7% and the relative standard deviations were 1.5%~13.1% at different spiking levels. The device has a strong enrichment capacity, and can be flexibly constructed and automated, which can be used for efficient monitoring of different pollutants in environmental water.