Based on the taking advantage of the remodeling of leisure fishing row and improving the device for single-fish target strength (TS) measurement in Daya Bay waters, the author measured and studied single-fish target strength of with Simrad EY60 portable scientific echo sounder (120 kHz) by tethering experimental methods in October 2008, which was video recorded in order to isolate the measurements on single targets. The experiment was set up in natural water and the live fish was held by thin wires. Experimental 16 fish samples of were all captured by fishing pot in situ in the same area. The fork length of ranged from 7.3 to 19.5 cm and the average of fork length was 11.3 cm; the weight ranged from 4.6 to 135 g and the average of weight was 33.2 g. The results show that the relationships between TS of pearl-spotted spinefoot (74.1. In this study, the split-beam technology was used for single-fish target strength measurement of different length fish in the South China Sea. The results from this research will facilitate the large-scale studies of single-fish target strength in South China Sea in the future, promote the local applications of fisheries acoustic technology, and improve the accuracy of the survey and evaluation of fishery resources by acoustics in South China Sea.