Experiment on rice-fish symbiosis in north China showed that the rice production in rice-fish field was a bit higher than control, and the output-input ratio of energy, utilization efficiency of solar energy and soil organic matter content increased 0.08, 0.1 and 0.24%, respectively. The banded sclerotic blight incidence decreased 3.8% and the net economic income increased 900 RMB yuan per hectare. All the resul;ts showed that rice-fish symbiotic system had a good symbiotic effect.