In order to investigate stress distribution of side plates on the logging truck’s cable reel, and find the cause of side plates cracking, an elastic-plastic finite element model of three-dimension is set up. Based on a series of computations, the distributions of displacement and equivalent stress under the working conditions are analyzed, as well as the influence of the number of side plate floors on stress distribution. The results indicate the maximum equivalent stress is on the outside connection between side plate and cable reel, and the floors take the most part loads from steel cables. When the number of floors is greater than 11, increasing the floor number will not decrease the maximum equivalent stress obviously. The conclusion provides useful method and foundation for resolving floor cracking on logging trucks.