In the previous paper, the authors discussed the larger angle of steady tilt can be induced by the wave-induced vertical steady forces on the lower hulls when the semi-submersible platform is moored in regular waves having short period. This curious phenomenon is considered to be dangerous to introduce the capsizing of the platform in violent seaway. However, as many existing rules concerning the platform stability requires the consideration of wind heeling moment for the design of the platform, this wind effects on the steady tilt must be taken into consideration as the another possibility of capsizing phenomenon of the semi-sub-mersible platform. This second report deals with an investigation of the magnitude of some environmental loadings on a eight-column twin hull semi-submersible platform for finding the possibility of larger steady tilt as well as the platform behaviors in such loading conditions. The timedomain simulation which was introduced in the previous report is used and some of the results are compared with experimental records for the purpose of their validity. Furthermore, the behavior of the semi-submersible platform in the combined environmental factors were studied by the simulation. As a result of study, the following conclusions are made. 1. The magnitude of current and wind induced loadings are comparable as well as that of the resultant steady tilt. 2. The wave-induced drift force and moment can be the same magnitude as other environmental steady forces and moments. 3. The magnitude of the moment due to the wave-induced vertical steady force may be the same order or more comparing with others depending on the submergence of lower hulls. 4. The results obtained by the computer simulation are agreeable with the experimental ones. 5. Concerning with the steady tilt in the combined loading condition, the effects of the wave-induced vertical steady forces on the lower hulls cannot be disregarded in the region where the larger wave-induced drift force arises.