Objective: To analyze the epidemiological characteristics of the differentiated thyroid cancer (DTC) in regions with different iodine intake levels and investigate the relation between the iodine level and thyroid carcinoma (TC). Methods: Based on the historical and pre-survey data, Pingtan county and Yongtai county of Fuzhou city were selected as high-iodine intake region and normal-iodine intake region, respectively, for this epidemiological investigation. The morning urine samples before breakfast from students in grade 3 at primary school in the two regions, for the year 2011, were collected, and their urinary iodine values were determined by arsenic-cerium catalytic spectrophotometric method. The detailed data on prevalence of TC in the two regions after national iodine supplementation program were obtained from Fujian tumor prevention and treatment center. Then, the prevalence of DTC and constituent ratio of the pathological types of TC were analyzed. Results: The iodine intake level of Pingtan county was significantly higher than that of Yongtai county in 2011 [(281.3±171.9) μg/L vs. (151.4±77.2) μg/L, t=18.44, P=0.00], and compared with previous years, the proportion of insufficient iodine intake was gradually decreased but the proportion of more than adequate or excessive iodine intake was gradually increased in Pingtan county; the proportion of insufficient iodine intake was gradually decreased and the proportions of adequate or excessive iodine intake tended to be stable, but the proportion of sufficient iodine intake was gradually increased in Yongtai county. From 2001 to 2011, the average annual incidence of DTC in Pingtan county was 52.725/100 000 and the standardized incidence rate was 50.945/100 000, which in Yongtai county was 1.837/100 000 and 1.780/100 000 respectively, and the difference between the two regions was statistically significant (P=0.00). The incidence of DTC in women was higher than that in men regardless of whether they were in high-iodine intake or normal-iodine intake region and, moreover, the percentage of females was much higher in high-iodine intake region (5.34:1 vs. 2.74:1, χ2=6.15, P=0.02). Compared with Yongtai county, the proportion of DTC in Pingtan county was higher (98.5% vs. 91.0%, χ2=23.95, P=0.00), and the papillary thyroid carcinoma (PTC) accounted for the majority (95% vs. 83.3%, χ2=4.76, P=0.03), while the anaplastic thyroid carcinoma (ATC) was far rarer (0.1% vs. 1.3%, χ2=8.49, P=0.00). Conclusion: The incidence of DTC has increased in both high-iodine intake and normal-iodine intake regions and, however, it is far higher in high-iodine intake region than that in normal-iodine intake region, and is more prevalent in women. The increasing trend of TC is mainly responsible for DTC and especially for PTC, with the ATC becoming even rarer, and this trend is especially obvious in high-iodine intake region.