In this paper, it is assumed that a field line oscillates at low latitude. The magnetic disturbances on the ground are calculated and the low-latitude Pc3 pulsations are simulated from basic equations. Comparing with Pc3 pulsations observed at low latitudes, it can be seen that the simulated results are almost as same as real observations. So this theory can explain the characteristics of both frequency and polarization for low-latitude Pc3 pulsations.