Objective To investigate the contamination of Norovirus （NoV）， Sapovirus （SaV）， hepatitis A virus （HAV） and hepatitis E virus （HEV） in marine shellfish and water bodies in Shandong Province， Weihai City.Methods From December 2020 to November 2021， a total of 360 samples including fresh shellfish， seawater and sewage were collected from local aquaculture farm， retail markets and sewage treatment plant. After virus particle concentration， nucleic acids were extracted and detected by real-time fluorescent reverse transcription polymerase chain reaction （RT-qPCR） for determination of NoV， SaV， HAV and HEV.Results The total positive rate of four viruses was 31.67% （114/360）. The level of four viruses contamination varied depending on samples types， and the rank of positive rate for different sample types was sewage， sea water， farmed shellfish and retail shellfish in descending order. NoV was the dominant contaminating virus with the total detected rate of 27.78% （100/360）， followed by SaV 8.33% （30/360）， HAV 3.61% （13/360） and HEV 1.39% （5/360）. The detection rate of the four foodborne viruses in samples varied with seasons， and it was the highest detection rate for farmed shellfish， retail shellfish and sewage in summer， with 53.33%， 30% and 100% respectively， and the lowest in autumn and winter. While for sea water， the highest detection rate for the four foodborne viruses was in winter （60%） and the lowest was in summer （6.67%）. In addition， 26.32% （30/114） of the positive samples were mixed contamination with two （26 samples） or three （4 samples） viruses. The occurrence frequency of the two virus mixed combination was NoV-SaV， NoV-HAV， NoV-HEV， SaV-HAVand SaV-HEV in descending order， and the combination of three viruses was NOV-SAV-HAV. The rank of detection rate of viruses mixed contamination in different sample types was sewage， seawater， farmed shellfish and retail shellfish in descending order.Conclusion There was a risk of foodborne viruses contamination in marine shellfish and water bodies in Weihai， and the contamination was seasonal. The issue of viruses mixed contamination needs to be concerned. Additionally， monitoring of foodborne viruses in marine shellfish should be strengthened in Weihai in summer.