The spatial distribution of nutrients structure and its controlling factors indicated by the dissolved inorganic nitrogen (DIN = NO3-+ NO2-), phosphate (PO43-), silicate (SiO32-)were studied, on the basis of two cruises in the Qiongdong sea during the winter of 2012 and the summer of 2013. The results indicated that during winter the high DIN, SiO32-, and the ratio of DIN to P, and Si to P appeared in the north of the surveyed sea. The nutrient concentration and ratio in the other stations were low and smoothly distributed. The reason for the phenomenon might be that the nutrient in the northern of survey sea were affected by Guangdong coastal current with high DIN, SiO32- and low PO43-. In the summer, the distribution of DIN and PO43- were similar to winter with a uniform distribution, while the SiO32- and ratio of Si to DIN, and Si to P were high in nearshore and low in the offshore. This was because of the near shore was affected by Hainan runoff with low DIN, PO43-and high SiO32-. It was also influenced by the high biomass and enhanced stratification in the near shore. Further analysis of the nutrients limitation for phytoplankton growth showed that in surface water there was an obviously Si limiting in winter, the relative frequency (%) of silicon is 58.83%. Similarly, it showed a coupling of N and Si limiting in summer. This might be related to the Biological needs, Seasonal river runoff, Guangdong coastal current and stratification, the limiting factor from Si change to Si and N.%研究了琼东海域冬季（2012年12月）和夏季（2013年8月）表层水体营养盐结构特征和营养盐对浮游植物生长的限制情况。结果表明：2012年冬季，调查海域除了北部站位DIN、SiO32-浓度和nDIN/nP、nSi/nP比值较高之外，其余站位营养盐浓度和比值整体比较低且分布比较均匀，这是由于北部站位受到了具有高浓度 DIN、SiO32-和低浓度PO43-的广东沿岸流的影响；2013年夏季，由于夏季河流径流量大，琼东近岸海域受到具有低浓度DIN 、PO43-和高浓度SiO32-特征的河流影响，同时夏季近岸生物量增大和层化作用增强，因此DIN和PO43-浓度分布比较均匀，SiO32-浓度和nSi/nDIN、nSi/nP比值呈近岸高离岸低的分布特点。进一步分析该海域营养盐对浮游植物生长的可能限制因子发现，表层水体冬季呈现明显的硅限制，其限制因子几率为58.83%，夏季呈现氮-硅协同限制的可能性。由于生物利用、季节性的河径流量、广东沿岸流以及层化作用的影响，使得营养盐限制因子由冬季的硅限制转变为夏季的氮和硅共同限制。
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