This research was to determine whether ultra-drying improves the vigor and storability of Ammopiptanthus mongolica seeds. Seeds of A. mongolica were dried to a 4.67%, 3.73%, and 2.24% moisture content (MC). After storage for 24 months, their level of vigor was measured. To determine whether these low MCs affect the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR), we evaluated the ability of dried seeds to germinate and to produce normal seedlings. Meanwhile, we also measured volatile aldehydes and malondialdehyde (MDA), lipid peroxidation production. Results indicated that the SOD, CAT, POD, APX and GR activities of ultra-dry seeds were higher than those of control seeds while volatile aldehydes and MDA were lower than in the control. The drying tolerance was related to a reorientation of the enzymatic antioxidant defence system. The electrical conductivity of ultra-dry seeds and controls showed obvious differences. All the results showed that ultra-dry storage is beneficial to maintaining the vigor of A. mongolica seeds. It is proposed that A. mongolica seeds may be stored in an ultra-dry state at ambient temperature for a long time.