In order to explore the pollution characteristics and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in coastal small watersheds, surface sediment samples were collected from the Houxi River in Xiamen and analyzed by gas chromatography - mass spectrometry (GC - MS). The results showed that the total content of 16 PAHs in the surface sediments of the Houxi River watershed in Xiamen ranged from 115.02 to 807.27 ng/g, with an average of 371.33 ng/g. Among them, 4 - ring and 5 - ring PAHs had the largest proportion, 2 - ring PAHs had the smallest proportion, and 3 - ring and 6 - ring PAHs were in the middle. Comparing the average content of PAHs at each sampling point, the upstream (A) had the lowest value (86.23 - 153.61 ng/g), the middle reaches (B) were in the middle (298.23 - 456.71 ng/g), and the downstream (C) had the highest value (435.24 - 656.11 ng/g), indicating that the PAHs value was directly related to the regional ecological environment. The ecological risk of PAHs was evaluated by the sediment quality guidelines (SQGs). The results of the ecological risk assessment at most sampling points were between the lowest - level Rare Effect Level (REL) and the second - lowest - level Threshold Effect Level (TEL), and a small part was at the medium - level Occasional Effect Level (OEL). None of the stations reached the threshold ranges of the higher - level Probable Effect Level (PEL) and the highest - level Frequent Effect Level (FEL). This indicates that the overall ecological risk of PAHs in the surface sediments of the Houxi River watershed in Xiamen is low. However, there are certain differences in the ecological risks of different sampling points and different types of PAHs, which deserve attention. The research results can provide support for regional pollution prevention, control and risk assessment.