The invention discloses an intelligent design method of the sections of steel truss beam rod pieces. The method includes the following steps of obtaining a plurality of thickness values of each platepiece in each rod piece according to the preset thickness range and difference of the plate pieces, arraying and combining the plate pieces in each rod piece according to the different thickness values to obtain n sections of the rod piece, calculating the sectional area, sectional inertia torque and sectional centroid position of each section, calculating the maximum internal force and minimum internal force of each rod piece under different load combinations, screening out the sections meeting target conditions from all the sections of each rod piece, selecting the corresponding section withthe minimum sectional area from all the sections meeting the target conditions to serve as the optimal section of each rod piece, and calculating the optimal sections of all the rod pieces of a steeltruss beam segment. The optimal section meeting the target conditions with the minimum sectional area is found out from all the sections of each rod piece. The method is high in design efficiency, isthe lowest in steel consumption and greatly saves cost.