The human factor reliability of the fixed offshore wind turbine installation operation is evaluated by Cognitive Reliability and Error Analysis Method (CREAM), and the traditional CREAM is improved by introducing structural entropy weight method and Markov method to realize the quantitative calculation of human factor reliability indexes such as human factor error probability and average human error time. With the full integration of realistic conditions and considering the influence of environmental and human factors such as weather, waves and operation level of the offshore wind turbine installation, the development suggestions are made in terms of operation quality, organization and management, and environment improvement in view of the requirements and characteristics of the fixed offshore wind turbine installation operations and the results of operator reliability assessment.