Wind turbine blade lifting construction is a key link in the construction of offshore wind farms. Blade lifting construction involves complicated construction steps and difficult construction techniques, and the construction phase is easily affected by weather, waves, equipment, man-made factors and so on. Therefore, this study provides a detailed risk assessment of offshore wind turbine single-blade blade lifting construction based on the IFMECA methodology. 12 failure modes and 25 failure causes were identified in the study, and the Risk Priority Number of the failure modes and the Criticality of the failure causes to the failure modes were calculated and obtained. According to the results, the most dangerous failure mode is FM4-Blade Lifting Failure with an IRPN of 6.66, which is mainly affected by factors such as weather conditions and human handling. The next most dangerous failure mode is FM3-Blade Mass Damage with an IRPN of 4.66, which is also affected by factors such as weather and human intervention. The results of this study help to improve the construction level of offshore wind turbine blade lifting, and can forecast the potential risks in the construction process to the engineers and put forward control measures, which has high economic value and engineering benefits.