Biological toxicity monitoring of water quality can reflect the comprehensive situation of water quality. The biological toxicity monitor for water quality based on fish behavior method is an important technical means for online monitoring and early warning of water pollutants. The image analysis method uses computer image tracking processing technology to identify and analyze the individual behavior and group behavior of fish, so as to realize the monitoring of biological toxicity of water quality. The performance evaluation of this type of biological toxicity monitor for water quality is studied, and its main indexes are divided into detection performance, data quality and operation and maintenance. The test method of each index is described respectively and experimental tests are carried out. The results show that the three types of indexes can be used to evaluate the ability to reflect water quality, the reliability of monitoring data and the performance in practical application of the biological toxicity monitor for water quality and can comprehensively reflect the performance of the instrument.