The analysis and evaluation of the power performance of tidal energy converters are crucial for promoting the iterative upgrading of tidal current energy generation technology. However, analysis of field testing datasets of tidal energy converters shows that the tidal current velocity data and output electric power data do not always have a one-to-one correspondence, which is not conducive to refined analysis of the power generation performance of tidal energy converters. In view of this, based on previous field test data, methods such as the Savitzky-Golay （SG） filtering algorithm, data interpolation algorithm, comparative analysis, and mathematical statistics were adopted to conduct research on the analysis methods of the power performance of tidal energy converters, focusing on indicators such as the output power, overall conversion efficiency, annual power generation, capacity factor, and annual equivalent full-load hours of the devices. The research results show that the SG filtering method has a good effect on filtering out the fluctuations of tidal current velocity data, especially for the tidal current velocity data in significantly oscillating intervals. The cut-in velocity characterized by the scatter plot of the output power of the tidal energy converter after interpolation is 0.5 m/s, and the cut-in velocity index is decreased by 7.4% compared with that before interpolation. The maximum output power in the dataset after interpolation is 542.9 kW, which is 0.6% higher than the maximum output power before interpolation. The maximum overall conversion efficiency in the interpolated dataset is approximately 43.4%, which is 1.9% higher than the maximum overall conversion efficiency of 42.6% before interpolation. The differences in the annual power generation, capacity factor, and annual equivalent full-load hours of the tidal energy converter between the datasets before and after interpolation are 700.8 kWh, 0.000 2, and 1.6 h, respectively. These findings provide a valuable reference for the refined performance analysis of tidal energy converters.