To clarify the response and adaptability of peanut under salt stress, Huayu 25 was used as the material, and non-salt stress (CK), 0.15% salt stress (S1), and 0.3% salt stress (S2) were applied as three treatments.  The study analysed the effects of salt stress on photosynthetic characteristics, photosynthetic substances accumulation and distribution as well as the ecological adaptability of peanuts.  The results showed that net photosynthetic rate (P_n), SPAD value, leaf area, and peanut yield were reduced under salt stress.  P_n in CK was 13.71 and 28.72% higher than that in S1 and S2 at the 50th day after planting, respectively.  At the same growth period, the SPAD value among treatments was ranked as follows: CK>S1>S2.  The 100-pod mass, 100-kernel mass, kernel rate to pod, and pod mass per plant were reduced under salt stress, and the trend was CK>S1>S2.  The distribution proportion of dry matter in different organs of peanut plant was changed to adapt to such stress.  Roots under salt stress intensively distributed in a 0–40 cm soil layer for salt resistance.  Dry mass proportion in stems and pods increased during the vegetative stage and early period of reproductive stage, respectively.  The maximum growth rates of the pod volume, pod dry weight, and seed kernel dry weight all declined, and the pod and kernel volume at harvest were reduced, improving the seed plumpness under salt stress.  This finding could be useful in growing peanut in saline soil.