The transmission of motion from one gear to the other in a planetary gear train usually result in unwanted conditions such as vibration due to poor gear assembly, high contact forces, high rotation speeds etc. The vibrating effect of the gear can result in higher or lower frequency response which may damage the gear or offer safe working condition. Using SOLIDWORKS 2018 version for the modelling, SimulationXpress was used to conduct frequency analysis on input shaft/carrier of a planetary gear train to understand its behaviour at different mode shapes during vibration. Results obtain from the input shaft/carrier frequency analysis showed natural frequency values of 1922.4Hz, 1922.8Hz, 2101Hz, 2183.1Hz and 2185.3Hz for mode shape 1-5. Geometry of the input shaft/carrier appeared differently at each mode number, resulting in frequency responses characterised by different modal shapes. This also led to gradual increase in the natural frequency of the input shaft/carrier at increasing mode no, consequently causing deflection on the mode shapes of the input shaft/carrier model. Hence, vibration should be reduced to the lowest limit of tolerance for minimum deflections and longevity of the input shaft/carrier and planetary gear components.