Abstract: Microplastics (<5 mm) is a type of emerging contaminants that has attracted much attention. However, the relevant study of distribution characteristics and influencing factors of microplastics in the intertidal zone of the coastal bays of Hainan Island is extremely limited. In this study, the distribution characteristics of microplastics in the intertidal sediments of 12 bays in southern Hainan Island were analyzed, and the risk level of microplastics pollution was assessed by using polymer index and pollution load index. Microplastics were detected in the intertidal sediments of 12 bays, with an average abundance of 715±135.98 n/kg. The spatial variation of microplastics abundance was obvious, and the highest abundance (2433.33±765.62 n/kg) was found in station XDH (Xiaodonghai) with significant difference (p<0.05) from other sites except Yazhou (YZ) bay, while the lowest abundance was found in LHT(Louhuitou), with a significant difference (p<0.05) from XDH and YZ. There was a significant positive correlation between microplastics abundance and total organic carbon (TOC) (p<0.05). The shape types of microplastics were fiber, fragment, film and granule, mainly fiber (66%) and fragment (31%). Microplastic colors were transparent, black, blue, red, brown, yellow and green, with transparent being the most abundant (94%). Microplastics were composed of polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyamide (PA), polylactic acid (PLA), polyvinyl chloride (PVC) and rayon, of which rayon, PE and PET accounted for the majority. The spatial distribution of microplastics with different polymers varied greatly. Combined with the polymer index and pollution load index, the microplastic pollution level in the intertidal sediments of the southern Bay of Hainan Island was at a moderate level, and it was speculated that domestic sewage input, tourism and fishery activities were the main sources of microplastics.