This paper develops a practical and user-friendly approach for real-time service load condition assessment of cable-stayed bridges.In this approach,the spatial effect of stress distribution is considered in the establishment of a 3D solid finite element model,and then the model is used to obtain the stress envelope.The real-time measurement data from the field and the theoretic stress envelope from simulation are used in the assessment of the service load condition.The design and field data are the basis of the assessment and this method can be applied widely in real engineering.A Case study has also been conducted,showing that the detailed procedure of the proposed method and results have advantages over the previous methods.