In order to study spatial distribution and movement of soil moisture and salt in coastal saline-alkali land and its effect on photosynthetic production and yield of cotton, and further discuss how elevation and soil bulk density affects spatial distribution of soil moisture and salt content in cotton fields of coastal saline-alkali soil, four cotton fields, quite different in elevation and soil bulk density were selected in a coastal saline-alkali area. Soil moisture and salt contents and soil pH in the 0~200 cm soil layers of the fields were monitored during the period of April~October and characterized for analysis of their influences on photosynthetic production and yield of cotton. Results show that in the cotton field, mild in soil salinity and alkalinity but high in elevation, a high-bulk-density interlayer was formed, 141~160 cm in depth, low in soil salinity and pH. In that cotton field, soil moisture content was low during the rainy season (July~August) and apparently higher than that in the cotton field moderate in soil salinity and alkalinity during the late cotton growing period (September~October). So the cotton in that field suffered less salt stress, and had its photosynthetic production highly coinciding with availability of prime hydrothermal resources and hence a long active dry matter accumulating period. In the cotton field, moderate in soil salinity and alkalinity and relatively high in elevation, higher elevation and bulk density inhibited rise of salt and pH, thus relieving the crop from salt stress during the rainy season, but salt stress was still quite obvious during the early and late cotton growth periods (April~June and September~October), so the crop did not have a good coincidence of its photosynthetic production with availability of prime hydrothermal resources. In the cotton field high in soil salinity and alkalinity and low in elevation, soil buld density did not seem to have much impact on water and salt movement, and the crop was subjected to a long-term high soil stress and hence low in capacity and yield of cotton. Therefore in ameliorating the coastal saline-alkali fields, it is advisable to raise them in elevation properly and help them form a high bulk density interlayer of a certain thickness, to improve them water storage and drainage capacity, which is believed to be a soil ameriolating measure contributive to photosynthetic production.