In order to study the influence of the random perturbation of time-varying mesh stiffness on the dynamics of the helical gearing system, based on Newton's law, a stochastic dynamics model of a six-degree-of-freedom helical gear system is established and dimensionless processing is carried out. Combining the bifurcation diagram, Poincaré map, Lyapunov exponent diagram, phase diagram, and time history diagram of system, the bifurcation characteristics of the helical gear system with considering the random perturbation of mesh stiffness are analyzed. Numerical simulation analysis results show, when the time-varying mesh stiffness of helical gears increases, the helical gear transmission system gradually shifts from periodic motion to chaotic motion by doubling bifurcation. The increase of random disturbance makes the system’s bifurcation characteristics change, and enters chaos in advance, the dynamics characteristics of the system have an essential influence. Therefore, reasonable parameters should be selected during design to ensure system stability.