Laizhou Bay and its adjacent waters are of great importance to China’s marine oil and gas development. It is therefore crucial to estimate return-period values of marine environmental variables in this region to ensure the safety and success of maritime engineering and maritime exploration. In this study, we used numerical simulations to estimate extreme wave height, sea current velocity and sea-level height in western Laizhou Bay. The results show that the sea-level rise starts at the mouth of the bay, increases toward west/southwest, and reaches its maximum in the deepest basin of the bay. The 100-year return-period values of sea level rise can reach 3.4–4.0 m in the western bay. The elevation of the western part of the Qingdong Oil Field would remain above the sea surface during extreme low sea level, while the rest of the oil field would be 1.6–2.4 m below the sea surface. The return-period value of wave height is strongly affected by water depth; in fact, its spatial distribution is similar to the isobath’s. The 100-year return-period values of effective wave height can be 6 m or higher in the central bay and be more than 1 m in the shallow water near shore. The 100-year return-period values of current velocity is about 1.2–1.8 m s-1 in the Qingdong Oil Field. These results provide scientific basis for ensuring construction safety and reducing construction cost. Laizhou Bay and its adjacent waters are of great importance to China’s marine oil and gas development. It is therefore crucial crucial to estimate return-period values ​​of marine environmental variables in this region to ensure the safety and success of maritime engineering and maritime exploration. study, we used numerical simulations to estimate extreme wave height, sea current velocity and sea-level height in western Laizhou Bay. The results show that the sea-level rise starts at the mouth of the bay, increases toward west / southwest, and reach the maximum in the deepest basin of the bay. The 100-year return-period values ​​of sea level rise can reach 3.4-4.0 m in the western bay. The elevation of the western part of the Qingdong Oil Field would remain above the sea surface During the extreme low sea level, while the rest of the oil field would be 1.6-2.4 m below the sea surface. The return-period value of wave height is strongly affected by water depth; in fact, its spatial distribut ion is similar to the isobath’s. The 100-year return-period values ​​of effective wave height can be 6 m or higher in the central bay and be more than 1 m in the shallow water near shore. The 100-year return-period values of current velocity is about 1.2-1.8 m s-1 in the Qingdong Oil Field. These results provide scientific basis for ensuring construction safety and reducing construction cost.