After the polar adventure cruise ship is launched, it needs to be moved to the dock side with tug pushing. Due to the relatively weak structure of the ship, the pushing structure strength must be checked. In order to analyze the structure strength of ship side under pushing force, the structure stress of ship side stern under pushing force is calculated based on finite element simulation method. The stresses of target beam under 1 span, 3 spans and 5 spans are calculated respectively by simplifying beam system calculation. Through comparative analysis, it can be concluded that: the more spans considered in the beam system calculation, the lower the X direction normal stress value calculated; when the beam system spans reach 5, the difference between the calculated results of beam system and finite element calculation value is only 1.6%. Therefore, in the pushing calculation, a 5-span beam system model can be established to replace the finite element calculation, which can obtain the results quickly and guarantee certain calculation accuracy.