Aiming to explore the regulation effect of biomass materials on water, salt and fertilizer transport in salt-affected soil under drip irrigation, an indoor soil tank experiment was carried out to investigate the influential law of two biomass materials, including biochar and humic acid, on the migration, redistribution and spatio-temporal characters of soil water, salt and nitrogen under the conditions of water-fertilizer integration and drip irrigation. The results showed that under drip irrigation, the spatial and temporal dynamics of soil water and salts consisted of two obvious processes: the transport process of soluble salts driven by water infiltration, and the redistribution process of soil water and salts induced by evaporation and diffusion. Ammonium nitrogen content showed temporal changes of first increasing and then decreasing, and the migration and redistribution characteristics were not obvious in space. Nitrate nitrogen exhibited similar migration and spatio-temporal distribution characteristics to those of soil water and salts, and it was also influenced by the nitrification of ammonium nitrogen. Biochar greatly improved the migration rate and distribution range of soil water, salts and nitrogen in the infiltration stage by significantly increasing the soil saturated hydraulic conductivity. Humic acid enhanced the range and intensity of soil water, salts and nitrogen in the redistribution stage by increasing the soil water holding capacity. Meanwhile, humic acid showed stronger inhibitory effect on the hydrolysis and nitrification process of urea. It was concluded that the application of biomass materials could not only regulate the soil water and salts transport by improving soil physical properties, but also affect the transformation, migration and distribution of nitrogen in salt-affected soil. The research result provided a theoretical basis for water-saving, salt-control and fertilizer-reduction management in saline farmland under water-fertilizer integration and drip irrigation.