Beibu Gulf is an essential region of the microplastic fluxes in the northwest part of the South China Sea and therefore in the Indo-China peninsula due to different coastal activities such as industry, tourism, urban development, intensive fishing, and loads of riverine discharge. Multiple samples from surface water, bottom water, and surface sediment were taken for this investigation. The results showed that in surface and bottom seawater, MP concentrations were 0.25 ± 0.25 items/m³ and 0.29 ± 0.29 items/m³, respectively, while 74.99 ± 37.53 items/kg in surface sediment. Statistical analysis and geographical abundance showed vise-versa phenomena as surface water and sediment had similar features while statistical analysis showed a negative relationship between these two. The mass balance of the box model showed that riverine discharge and atmospheric deposition account for a substantial portion of MPs (50%) whereas the South China Sea (SCS) receives 49% of MPs discharged from Beibu Gulf, and just 1% is deposited in sediment annually, which could explain the vise-versa phenomena between statistical analysis and geographical distribution of microplastics. Nonetheless, it is revealed that human activities and coastal influence have a more significant impact on microplastic abundance and distribution in the Beibu Gulf.