According to the theory of small deformation and combing with the simplified model of the pallets and the deformation formula of variable thickness plate, the maximum deflection formula was deduced when the pallet is under complex load of three working conditions(ground-load, fork-lifting, upper carriage). However, the solving process was quite complicated because of the load function and bending rigidity function. Therefore, it is very necessary to discrete the maximum deflection formula. The benefits of discretization are easy to programming and providing a convenient way for researching the influences of panel structure on maximum deformation. The result showed shown that the discrete approximate maximum deflection equation can ensure the precision requirement, and the relative error is less then 0. 4%. Finally, the software applications of the algorithm were shown.