Abstract: Numerical prediction on environmental loads for the first 40 MW floating photovoltaic power station built in China is carried out. Based on the verification from the comparison with the measured data in a wind tunnel, a CFD (Computational Fluid Dynamics) method is applied to study the wind load and the current load on a large-scale square array. CFD numerical investigation verifies it feasible to adopt a simplified floating body model instead of the original one. The computational results of the model monomer are in a good agreement with the wind tunnel measured data. The 3D full scale square array's simplified calculations based on a coarse grid are carried out, and the distributions of wind loading on the array under various wind direction angles are obtained. Through the analysis of the distribution of maximum wind loading at north wind, the strategy of 2.5D calculation is put forward and numerically verified. According to the computational results, an 18(row)×11(column) scale model array test plan is designed and performed in a wind tunnel. The measured results are in a good agreement with CFD results, thus a global numerical calculation algorithm is set up. The 2.5D calculation based on a fine grid provides correction coefficients to rectify the 3D computational result to obtain more accurate wind loads. The calculation method for current loads is similar to that of wind loads. The numerical computation and analysis on the wave load are performed by the potential flow method. The wave load variations, at regular waves with unit wave amplitude, along the row or the column are obtained. According to the variation, the whole wave load is estimated. The wave load on the array is predicted at the extreme condition of a fifty-year return period. This study provides a method for the numerical prediction of wind loading, current loading and wave loading on a floating photovoltaic power station. The researches provide a technical support for anchoring the calculation of floating square array and the system design of floating photovoltaic power stations.