Abstract: As the increasing demand for quality management of marine ecosystem monitoring and lack of the assessment methods for marine biological monitoring data, a new method for phytoplankton identifying proficiency test has been developed and applied for the national phytoplankton sample identifying proficiency test in 2016.This test was organized by the State Oceanic Administration to assesse the phytoplankton identifying ability for state marine environmental monitoring agencies.The results showed that this method provided good measures and meeted the requirements of the relevant norms.The evaluation results were scientific and reasonable, which could be applied to the quality control of marine ecosystem monitoring.Generally, the ability of phytoplankton identification was tested in the current marine monitoring agencies, which will highly improve of the monitoring capability of these agencies.