The self-reversal process in the reversed-field pinch is studied in detail by means of a resistive magnetohydrodynamic simulation. It is confirmed that self-reversal can be caused by non-linearly driven reconnection resulting from the m = 1 global kink instability, as was previously proposed by the authors. The dependence of the degree of field reversal on the pinch parameter θ and on the instability mode (resonant and non-resonant) is examined. The results are consistent with theoretical predictions. Taylor's conjecture that the total helicity is a better conserved quantity than the total magnetic energy during the relaxation process is numerically confirmed. It is found that this conjecture can be consistently explained by the non-linearly driven reconnection model. It is also found that the single helicity relaxation process has a definite energy offset from Taylor's minimum energy state. Hence, a totally relaxed state cannot be achieved through the single helicity relaxation process. Finally, the dependence of the reversal process on the resistivity is examined