In this paper a new automatic frequency control (AFC) scheme was proposed,which could be used for the receiver of low earth orbit (LEO) satellite communication system in continuous transmitting scenario.By employing the time varying characteristic of particle filter technique,the new scheme combined the preamble based estimating step and data based estimating step to provide initial probability density recursively.Theoretical analysis proved that the proposed AFC scheme could provide better performance than the two-step scheme.The same conclusion was achieved by computer simulations with the criteria of root-mean square (RMS) frequency estimating performance and bit error rate performance.