Damage degree assessment is critical for the prognostics and maintenance of rotating equipment. Lempel-Ziv complexity has been widely used for rotating equipment quantitative fault diagnosis. However, traditional Lempel-Ziv complexity indicator extracts fault information only at the single scale, and it is difficult to fully explore fault features. Thus, scholars proposed the multiscale Lempel-Ziv complexity. However, multiscale analysis would shorten the length of time series and lead to inaccurate assessment results easily. Therefore, this paper proposes a damage degree assessment method for rotating equipment based on variable-step multiscale fusion Lempel-Ziv complexity (VSMFLZC). Firstly, the variable step length strategy is adopted to optimize the coarse-grained procedure and explore the fault information more comprehensively. Then, a fusion method based on Laplace score weighting is applied to evaluate the importance of each scale and the method can convert variable-step multiscale complexity sequence into a single but comprehensive evaluation indicator, i. e. the proposed VSMFLZC, which is used to explore the characteristics of the vibration signal comprehensively and achieve the damage assessment of the rotating equipment. The effectiveness of the proposed method is verified with bearing singlepoint defect dataset, bearing life cycle dataset and gearbox fatigue test dataset. Meanwhile, the indicator is compared with other complexity indicators. Results show that the proposed indicator can assess the fault severity of bearings and the wearing degree of gears with 100% accuracy, detect early failures and realize the quantitative diagnosis of rotating equipment.