The research of scattering property of small particles in electromagnetic beams has comprehensive applications in fields such as environmental monitoring. The electromagnetic beam is expanded in series, and the theoretical solutions of the internal fields for small particles as well as the physical significances of the items in these series are developed. Taking the elliptical beam as an example, the internal electric field and the changes of the ratio of the latter item to the former of the series, versus both the distance and the frequency are simulated. The scattering property of small particles in an elliptical Gaussian beam is investigated. By simulations, the effects of the beam waist and the frequency on scattering property are analyzed. The validity of the algorithm used is demonstrated. Results show that the beam waist may improve notably the particle′s identification, the scattering field of higher order item is much smaller than that of lower order item, and the power order of coordinates in the solution of internal field, speaking to a Rayleigh particle, is always equal to that of coordinates in the incident beam. The method used is simple and has explored a new way for scattering from particles in electromagnetic beams.