To investigate soil fertility status of coastal tidal flat saline-alkali farmlands in Yancheng City, Jiangsu Province, a total of 108 (0-20 cm) soil samples were collected based on the duration of reclamation, soil pH, total salinity (TS) and nutrients were measured, their spatial distribution characteristics were analyzed using geostatistical methods, soil integrated fertility indexes (IFI) were calculated with the modified Nemerow index method, and the primary factors influencing IFI were elucidated. The results showed that: 1) The spatial correlations of soil pH, TS and total phosphorus (TP) were moderate, while the block-base ratio of soil nutrients exhibited strong spatial autocorrelation, which suggested that soil nutrients were more significantly constrained by natural conditions. 2) The contents of soil organic matter (SOM), total nitrogen (TN) and alkaline-hydrolyzable nitrogen (AN) gradually decreased from west to east, which were contrary to that of soil pH, TS, total potassium (TK) and available potassium (AK). 3) Soil IFI was lower, with reclamation duration, salinity-alkalinity barriers, and nutrient factors accounting for 93% of IFI variation. SOM had the most significant impact on soil IFI. SOM was significantly positively correlated with soil IFI in all short, medium and long-term reclamation years, indicating that SOM acted as the fundamental factor for soil IFI. Hence, the enhancement of coastal saline-alkali farmland should be focused on the organic regulation in order to elevate the content of soil organic matter, and ultimately promote the capacity of soil nutrient reservoir.