The influence of feeding accuracy of gear train on printing quality, in particular the banding problem, for the ink-jet printer was explored in the paper. One method of band spectrum, as to mathematical method, was first presented to study the banding problem of print that was often encountered due to bad feeding accuracy of gear train of printers. Following the method, one physical model was then built up to solve a specific band problem, which was totally comprising of seven gears in the delivery train. Thus, some experiments for the feeding accuracy of the gear train were done for numerical analysis. At the mean time, there were two specified test patterns to be printed such that two individual groups of experiments were used to capture the cause of problem. As a result, it's found that one special gear, named cam gear, caused the problem mostly. The most of banding problem caused by the accuracy of gear train can disappear much after the cam gear was taken away in the train. This method could be expectedly a helpful tool to analyze the influence of feeding accuracy of gear train in many types of printers in the future.