Abstract: After coastal areas discharge antibiotic-containing wastewater into nearshore seawater, a dynamic adsorption-desorption process takes place in both the water and sediment phases. To investigate the occurrence characteristics and partition patterns of antibiotics in the effluent receiving areas (ERAs), we quantitatively analyzed the concentrations of six classes of 77 antibiotics in nearshore ERAs (JX and SY) and in coastal areas of Hangzhou Bay (Hangzhou Bay, HB), using ultra-high performance liquid chromatography and mass spectrometry. The results indicated that quinolones (QNs) were the predominant antibiotics detected in the sediments, and the total concentration of antibiotics decreased significantly from the nearshore ERAs to the coastal regions. In the nearshore areas of JX and SY, the total antibiotic concentration ranged from 2.3 to 132.2 ng/g (mean: 34.8 ng/g) and from 2.0 to 133.3 ng/g (mean: 74.7 ng/g), respectively. In contrast, the total antibiotic concentration in the coastal HB regions ranged from 2.2 to 51.9 ng/g (mean: 15.6 ng/g). Nine antibiotics were detected together with the detection frequency exceeding 50% in the water and sediments of the two of nearshore effluent receiving areas. Enrofloxacin (ERFX), ofloxacin (OFX), marbofloxacin (MBFX), and nadifloxacin (NDFX) were found to transfer from water to sediments greatly in SY. Their partition between the two phases showed a positive correlation with the physicochemical properties of the sediments but a negative correlation with water quality. Tosufloxacin tosylate (TSFX), roxithromycin (RTM), clarithromycin (CLM), 4-epichlortetracycline (ETC) and methacycline (MTC) transferred from water to sediments greatly in JX, with their partition between the two phases positively correlated with water quality but negatively correlated with the physicochemical properties of the sediments. The partition of antibiotic concentrations results in a corresponding partition of ecological risks. The ecological risk posed by antibiotics in water is significantly greater than that in sediments. Among the antibiotics, the risks associated with ERFX, NDFX, MBFX, and OFX in water are relatively high, primarily affecting fish, followed by green algae and water fleas. Additionally, the ecological risk of antibiotics in the water of the JX area is considerably higher than that in the SY area. This study is of great significance for assessing marine ecological health, controlling antibiotic pollution, developing remediation technologies, and formulating management policies.