The controller of paralleling small single phase synchronous generators should restrict the dash currents in generators below a defined value when it switches on. A field-circuit coupling time-stepping finite element model of the parallel system is built. The computation program is written in APDL languages of ANSYS and the transient process of paralleling two single phase synchronous generators in various parallel parameters are studied. The value and variation of the dash currents in two generators when switch on at various differences of three parallel parameters are analyzed and the accurate parallel conditions are provided to the parallel controller.