Low frequency longitudinal vibration of the vehicle is one of the key factors affecting the drivability of the vehicle, therefore the mechanism analysis and control of the vehicle longitudinal low frequency vibration have been a hot topic in vehicle NVH field. There have been a lot of conclusions about low frequency longitudinal oscillation and resonance vibration of the vehicle as long as related control methods. This paper analyzes the external influences brought by uncertain factors on the low frequency longitudinal vibration. Firstly, a low frequency dynamic vehicle model is built and it is used to simulate the vehicle's response under some uncertain factors in tip-in maneuver to discover the influences of uncertain factors on the longitudinal vibration. And then, three feedback controllers using PID algorithm are designed based on different control targets and co-simulate with the vehicle model under the same working conditions. By comparing and analyzing the simulation results, some useful conclusions can be obtained, which help us understand the mechanism and control the longitudinal vibration of vehicles better.