Soil salinization is the most important factor that restricts the soil quality in the newly coastal reclamation area, which seriously inhibits the growth and yield of crops. Six treatments including control treatment (CK), organic fertilizer (OM), polyacrylamide+organic fertilizer (PAM+OM), straw mulching+organic fertilizer (SM+OM), buried straw+organic fertilizer (BS+OM), and bacterial fertilizer+organic fertilizer (BM+OM) were set up to study the effects of different amelioration on soil salinization in coastal saline-alkali soil, and to identify the main factors controlling the variation of soil salinization degree. The results showed that the salt content, sodium adsorption ratio, and exchangeable sodium percentage of surface soil gradually increased, while the pH decreased gradually with the growth stage of oats. Compared with CK treatment, PAM+OM, SM+OM, BS+OM, and BM+OM treatments could significantly reduce soil salinity, pH, sodium adsorption ratio, and exchangeable sodium percentage at 0-20 cm depth. Among them, SM+OM treatment had the best inhibition effect on soil salinity, reaching 68.0%~73.6%, while BM+OM treatment had the best inhibition effect on pH, sodium adsorption ratio, and exchangeable sodium percentage, which decreased by 4.5%~8.2%, 61.5%~80.8%, and 55.5%~79.4%, respectively. The analysis of key influencing factors showed that the effects of soil bulk density, soil water content, and evaporation on the salinization degree of surface soil reached an extremely significant level (P<0.01), while the effects of wind speed and precipitation reached a significant level (P<0.05).