Contents of inorganic nitrogen (NH 4 + − N and NO 3 − − N) in soil profiles were measured in five typical zones ( including permanently flooded floodplain (B), 1-year floodplain (O), 5-year floodplain (F), 10-year floodplain (T), and 100-year floodplain (H) ) from Huolin River floodplain in Erbaifangzi, Jilin Province of China, in the soil-defrozen period (May of 1999). Contour maps and profile maps were constructed to describe the spatial distributions of NH 4 + − N and NO 3 − − N in order to identify the influences of flood frequencies on them. Results showed that NH 4 + − N generally increased with depth in soil profiles from the five areas, but NH 4 + − N contents in T or H areas significantly differed from those in other areas. For NO 3 − − N, with the exception that there was a significant cumulative peak (6.77±’.08 mg kg−1) at 15-cm depth (10-20 cm) in B area, NO 3 − − N contents in soil profiles from the other four areas. The horizontal distributions of NH 4 + − N and NO 3 − − N in top soils (0–10 cm) were different in the five areas, which were greatly influenced by flood frequencies. The highest content of NH 4 + − N or NO 3 − − N did not appear in B area but in the floodplain with certain flood frequency. For example, NH 4 + − N content (16.81 mg kg−) in 5-year floodplain wetland was highest, and the highest content of NO 3 − − N (1.69 mg kg−) appeared in 1-year floodplain wetland. In addition, NH 4 + − N contents were significantly correlated with soil pH, and NO 3 − − N contents had significant correlation with inorganic carbon, but there were no significant correlations between inorganic nitrogen and other selected soil properties.