Based on nonlocal Euler-Bernoulli beam theory, the dynamic characteristics analysis model for nanobeams resting on viscoelastic foundation and subjected to a magnetic field was built. The Kelvin viscoelastic foundation model and the Lorentz magnetic force were introduced to derive the governing equations of the system. The new general analytical expressions for the complex natural frequencies of the nanobeams were obtained on the basis of the Kelvin-Voigt model and some typical special cases were also discussed. Then the governing equations of motion were solved by using the transfer function method to obtain the natural frequencies and corresponding mode shapes in closed form for the nanobeams with arbitrary boundary condition. Considering a single-walled carbon nanotube as a numerical example, the first three natural frequencies under various boundary conditions were obtained, and a detailed parametric study was conducted to examine the effect of nonlocal parameter, the strength of the magnetic field, the aspect ratio, the damping parameter and the boundary conditions on the vibration characteristics of nanobeams. The results demonstrate the efficiency of the proposed model for dynamic characteristics analysis of the nanobeams resting on viscoelastic foundation under a magnetic field.