The water quality natural breed field of Guangdong black myers in Xijiang river system was monitored andanalysed by establishing 6 inspection sites duriy of spawn period Guangdong black myers in 2001. The water quality wasevaluated by 20 items including water temperature, pH, DO, ammonium, phosphate, nitrite et al. In Qingpitang fishery,onlyphosphate is over the standard and the standard-exceeding rate was 100%. In Luopang fishery,had three items ware over thestandard. The rate of both suspended solids and phosphate was 100%,and that of ammonium nitrogen was 33.3%. Other itemswere normal. The average synthetical index of water pollution was used to value the water quality of both fisheries. Thephosphate pollution was the most serious in the twenty items. The sharing rate was 63.49% in Qingpitang fishery and 46.09% inLuopang fishery. The synthetical index of water pollution was 0.59 in Qingpitang fishery and 0.52 in Luopang fishery,whichindicated that the pollution degree is not high.