Based on a case of offshore artificial island engineering,we establish a spatial elastoplastic finite element model for the stability analysis of the cellular steel sheet pile structure by employing PLAXIS 3D finite element software to study the deformation and stability properties on soft foundation and analyze the influence of the composite foundation on the stability the quay wall structure.Results show that reinforcement of the soil inside and outside of the cellular sheet pile improves the structural stability to different degrees.Especially,when the jet grouting piles is constructed inside the offshore artificial island,the stability of the quay wall structure increases greatly and the maximum post-load settlement of the artificial island could be effectively controlled.The research may serve as reference for the design and application of this structure on soft foundation.