Wheat cultivars Yangmai 12 and Huaimai 17 were selected to investigate the effects of post-anthesis salt application (ST), waterlogging (WL) or both (SW) on the absorption of K+ and Na+ ions, grain dry matter accumulation, as well as on redistribution of sugars and of amino acids. Contents of Na+ in leaves and stems and sheaths increased rapidly, while contents of K+ and the ratio of K+/Na+ decreased under the ST and SW treatments. This led to an ion imbalance between K+ and Na+ in wheat vegetative organs. WL, ST and SW reduced the contents of total soluble sugars, sucrose and of free amino acids in the grains. In stressed plants, both the rates of remobilization of total soluble sugar and of ‘pre-anthesis’ stored total soluble sugars of in vegetative organs were reduced. Consequently, grain filling was inhibited, and grain weight and starch content reduced. The impacts on these traits were much more severe under ST and SW treatments than in the control and WL treatments. SW and ST showed more severe impacts in Huaimai 17 than Yangmai 12, where grain weight was reduced by 60.3% and 61.1% in Huaimai 17, and by 46.6% and 43.7% in Yangmai 12, respectively. In addition, Yangmai 12 was more sensitive to ST than to the SW treatment, while Huaimai 17 was more sensitive to SW than ST conditions.