Liver ferritin of Sphyrna zygaena(SZLF) with purity of mass spectrum was prepared in batch. Under) the condition of acidifying medium at pH 1.0, PAGE showed that SZLF subunits treated for 20 min began) to dissociate. A whole process of subunit dissociation and recombination was monitored by transmission electron microscopy(TEM). In addition, the changes of size of both protein shell and iron core were also determined) by TEM directly. It was found that in the acid dissociation process of SZLF subunits, the size of iron) core and protein shell showed the same trend of change, which might be related to not only the iron release) of inner iron core but the dissociation and unfolding of the protein shell. The passway of SZLF recombination is a fast step, which is a conversion process from incompact moltenglobule to compact ferritin. Under the assistant of matrix acidity pH 3.0 and laser, SZLF mixed with horse spleen ferritin(HSF) still has capacity to release) its subunits to form subunit ions for mass analysis by a MALDI-TOF mass spectrometer, which indicates that the interaction intensity between the subunits was weaken but they were not unfolded under this pH condition. TEM technology can be applied in studying both dissociation and recombination in ferritin subunits.