Sodium (Na⁺), potassium (K⁺) contents and Na⁺/K⁺ ratio are the key indexes that affect the salt tolerance of rice. The salt tolerance of rice is controlled by quantitative trait loci (QTLs). At present, a number of quantitative trait loci for Na⁺ and K⁺ contents, as well as the Na⁺/K⁺ ratio, have been identified at the seedling stage, but few have been identified at the field growth stage. In this study, using a recombinant inbred line (RIL) population derived from a cross between ‘Dongnong 425’ and ‘Changbai 10’, dynamic QTLs for Na⁺ content, K⁺ content and the Na⁺/K⁺ ratio were identified by a combined analysis of salt stress and control conditions at different developmental stages during the field growth stage of rice. The additive (A), epistatic (AA), and QTL × environmental interaction effects (QE) of these QTLs were analyzed using a mixed linear model (MCIM). The results show that: (1) under the salt stress condition, the Na⁺ content of stems (SNC), Na⁺/K⁺ ratio of stems (SN/K), Na⁺ content of leaves (LNC) and Na⁺/K⁺ ratio of leaves (LN/K) in parents and RIL population were all higher than those of the control at each stage, while the K⁺content of stems (SKC) and K⁺ content of leaves (LKC) were all lower than those of the control. There was no significant difference of traits between parents at most stages under control condition. Under the salt stress, a number of traits of the two parents were significantly different at different development stages, among which SNC and LKC were significantly different at four stages, SN/K and LN/K were significantly different at three stages, and SKC and LNC were significantly different at two stages. (2) In total, 13 additive and 11 epistatic QTLs, including 14 unconditional and 10 conditional QTLs were detected using unconditional and conditional QTL mapping methods. We noted that 8 out of 13 additive QTLs and 7 out of 11 epistatic QTLs had significant QE effects. (3) qSKC51 was detected at four developmental stages, suggesting a key role in regulating the salt tolerance of rice. The additive × QE effect was detected in all QTLs of SNC, SN/K and LN/K, and the epistatic × QE effect was detected in all QTLs controlling SNC, indicating that the QTLs of these traits were more sensitive to salt environment. The present study demonstrates that the expression of QTLs for Na⁺ content, K⁺ content and Na⁺/K⁺ ratio in rice during the field growth stage was closely related to the developmental stages. The heredity of salt tolerance of rice under field growth condition is very complex. Epistatic and QE effects should be considered in producing new salttolerant rice materials by molecular markerassisted selection (MAS).