Abstract: Benthic macrofauna are common in coastal wetlands. It was reported that some benthic organisms such as Acaudina molpadioides and so on blocked the water intake system of coastal nuclear power plants (NPPs). Accor-ding to the data collected by bottom sampler from 52 sampling stations on the subtidal zone in Daya Bay over four seasons from October 2017 to July 2018 and Acaudina molpadioides collected by bottom trawl in March 2021, two risk indices, namely grappler method risk index (GMRI) and bottom trawl risk index (BTRI), were developed based on the evaluation of benthic organism entrapment on the water intake system in NPP. Among 7 benthic species in Daya Bay, the GMRI of species exceeded 50% included Aglaophamus dibranchis in winter and spring and Listriolobus brevirostris in summer. While the GMRIs of Apionsoma trichocephala, Paraprionospio cristata, Paratapes undulatus, Acaudina molpadioides and Protankyra bidentatawere less than 50%, which were classified as low risk or minimum risk. In March 2021, the BTRI of Acaudina molpadioides at station D13 in Daya Bay was 65%, which was classified as high risk. The BTRIs of Acaudina molpadioides at stations D11, D21 and D31 were 31%, 19% and 33%, respectively, which were classified as low or minimum risk. The advantage of the grappler method is that it can quantitatively calculate the density, biomass and occurrence frequency of benthic species, but the disadvantage is that it is difficult to collect animals with similar morphological characteristics as Acaudina molpadioides. The advantages and disadvantages of the bottom trawling method are the same to the grappler method.