含有少量磷酸根的三价铁盐的水解机理是相当复杂的，这个过程可分为两个阶段，即：成核前的水解机理和成核后的水解机理．本文应用Ｆｅｒｒｏｎ逐时络合比色法研究了前一个阶段的水解机理．此法把三价铁水解过程中的形态区，分为Ｆｅ（ａ）、Ｆｅ（ｂ）和Ｆｅ（ｃ）三类，它们分别代表了三价铁盐水解产生的不同聚合度的聚合物．并根据三价铁回收曲线的形状间接确定了磷酸根的位置，阐明了为什么磷酸根的存在会对三价铁盐溶液的水解产生抑制作用，该结果对均匀纺锤形α－Ｆｅ２Ｏ３粒子的制备具有一定的指导意义． The hydrolysis mechanism of trivalent iron salts containing a small amount of phosphate is quite complicated. The process can be divided into two stages, namely, the pre-nucleation hydrolysis mechanism and the post-nucleation hydrolysis mechanism. Ferron’s time-lapse colorimetric method was used to study the hydrolysis mechanism of the previous stage. The method divides the morphological zone of trivalent iron into three types: Fe (a), Fe (b) and Fe (c), which respectively represent the polymers with different polymerization degree produced by ferric salt hydrolysis. And according to the shape of the recovery curve of ferric iron indirectly determine the position of the phosphate, clarify why the presence of phosphate will inhibit the hydrolysis of ferric salt solution, the results for uniform spindle-shaped α-Fe2O3 particles with A certain guiding significance.