Abstract: Objectives Design a practical adhesive connection structure between composite deckhouse and steel main hull, then to evaluate the bearing property and failure behavior of local joints under the overall load of deckhouse. Methods By using the sub-model approach, the local joints part is correlated with the whole deckhouse model, and the parametric analysis on adhesive layer is conducted by numerical simulations aiming at the composite-steel slot connection scheme. After that, we evaluate the mechanical response characteristics of the connection position at root of ship deckhouse under the action of splash load, and carry out the local destructive experiment to investigate the local failure mode of the real-size connection sample. Results Calculation results show that under the overall load of spray splashing, the stresses to be examined in all parts of the adhesive connection structure are less than their ultimate capacity of material, and a certain safety margin is retained. When the load is about 3 times size of standard load applying upon connection structure, the initial damage can be mainly found at the corner of the stiffening beam skin. When the load reaches about 10 times size of standard load, the stiffening beam skin is almost totally failed. Besides, the damage features revealed by actual loading test are basically consistent with the analysis results of refined local joints model. Conclusions This proposed slot adhesive connection structure is reliable and effective to meet the requirements of the strength performance between composite deckhouse and steel main hull, which can provide useful reference for engineering application of composite superstructure in the ship industry.