Abstract: The dilatometric method has been used to compare the difference of the longitudinal （parallel to tensile direction） and transverse （vertical to tensile direction） recovery rate of Fe-30Mn-6Si-5Cr alloy in this paper. The effect of prestrain on longitudinal recovery quantity, recovery rate, A_s and A_f has been studied. The recovery rate affected by thermal cycling following prestrain has been studied. At same time, some significant information was obtained by repeated heating and cooing a large prestrain specimen in different temperature range between A_s and A_f. Moreover, the influence of tensile prestrain on the amount of defects, the alloy density at defects and the amount of γ→ε transformation has been examined by using positron annihilation technique in aging and nonaging Fe-30Mn-6Si and Fe30Mn-6Si-5Cr alloys.