Abstract: Total of 107 Leiocassis crassilabris caught in Huangzhou along the Yangtze River from May to July 1999 were examined for infection by Leiocassis crassilabrisThe infection rate of the host was 84.1%The infection rate of the host with body Length 12.0-16.0cm was the highest,while no Leiocassis crassilabris was found in the host with body length above 28.0cm.The infection intensity of the host was 23.5.There was a negative correlation between body length and infection intensity of the hostr=-0.9043.Parasite population was mainly composed of parasites with length below 30 mmThe females were more than the males obviouslyDistribution of Leiocassis crassilabris was clumped in the host population.

Key words: eco-economic, emergy analysis, Liaoning Province.