Random, errors are ubiquitous in measurements of gravity and magnetic data, mathematical transformation processing of various kinds as well as direct and inversed calculations. One of the factors causing the instability of gravity and magnetic inversed solutions seems to be the existence of stochastic disturbance which, during the downward continuation and the calculation of derivative of higher degree, frequently enlarges the errors to an excessive extent, thus distur bing seriously the useful anomalies and making them unrecognizable.With a. purpose of looking into the influence of random errors on gravity and magnetic transformation, the author has made a deep investigation into the propagation of random errors in frequency domain.