Abstract: Pallet stacked unit of bulk cargo is a common form of transportation packaging. This paper investigates experimentally the product acceleration response of pallet stacked unit of bulk cargo under random vibration excitation，and the mechanism of product response is analyzed. The influence of excitation spectrum，vibration level，constraint and product position is also discussed.The experiment results show that the product acceleration response at each layer is mainly controlled by the first resonance frequency，and that at the bottom is controlled together by higher order frequencies. The excitation spectrum type，especially the power spectral density in the first resonance region，has an important influence on the product response of the unit. When the vibration is large，the acceleration response of the bottom product is significantly different from that of the upper product，and a separation between the bottom products and supporting pallet or upper products occurs，which leads to a larger shock signal，resulting in the super Gaussian distribution of the acceleration response of the bottom product. The asymmetry（nonlinear）of tension and compression of the strapping leads to the asymmetry of the acceleration response signal and its left-skewness super Gaussian distribution.The stretched film wrapped strengthens the restraint of the strapping on the unit，and effectively inhibits the response of the product.