Stock enhancement and releasing is one of common and effective technique in the wild resource protection and restoration. Nevertheless, missing an effective mark-recapture method makes it hard to evaluate the effect. By the benefit of non-toxic, harmless and long retention time, microchemical marking (i.e. strontium) become an effective means. Here we developed a fin ray strontium marking technique. The larvae, blunt snout bream ( Megalobrama amblycephala Yih, 1955) was marked in the 800 mg L -1 SrCl 2·6H 2O solution for 5 days before a 20-day recovery culture in normal water. The section of dorsal fin rays was extracted to analyze the Sr concentration distribution in the plane by using electron probe microanalysis (EPMA) with accelerating voltage of 15 kV and beam current of 0.36 μA. It showed that the determination condition of 15 kV, 0.36 μA could obtain the obviously visual and accurate distribution map of Sr concentration in the fin rays, with minimum damage. The dynamics of Sr mark in fin ray coped well with that of Sr immersing process of the experimental fish. By the meantime, a 3D mesh image was also used, which was able to reflect more details than the normal 2D mapping result. Non-lethally samplable fin ray can completely replace lethally sampled otolith for accurate evaluation the Sr marking effect by using EPMA with accelerating voltage of 15 kV and beam current of 0.36 μA. The method had immensely practical value in the experimental development of restocking methodologies with the advantages of objectivity, accuracy and visualization.