The CAD/CAE technical was used to study structure and dynamics characteristics of thin-walled parts. Based on a type of thin-walled part, its finite element model of was set up on WorkBench platform, and some low order natural frequency and vibration mode of its structure were also calculated and analyzed. Four structure design schemes about improving dynamic characteristics of the part was established, and then an optimal structure of it was determined through calculating and analyzing its dynamic parameter. The results indicated that vibration resistance of the part could be strengthened effectively by using the cross rib structure, and it was also advantageous to vibration noise reduction and high speed operation of machinery equipment as well. The study provided some important technical reference for structure design and dynamics optimization of thin-walled parts.