Abstract: Downburst is a type of extreme convective weather that can cause significant structural damage. The wind loading acting on transmission towers in the wind-resistant design codes has not yet considered the effects of downburst winds. Therefore, this study employs numerical simulation and introduces a gust-front factor method that accounts for unsteady downburst wind effects. And incorporating ground roughness effects as per Chinese standards, an improved gust-front factor method for the equivalent wind load on transmission towers under downburst conditions is proposed. To verify the accuracy of this method, the results of time history analysis and equivalent wind load analysis under unsteady downburst wind effects were compared using six transmission tower cases of different heights and two wind profile conversion standards. The analysis results indicate that the equivalent wind loads calculated with the improved gust-front factor method better reflect the characteristics of downburst wind fields. The equivalent static wind response calculated using this method effectively envelopes the peak values obtained from the time history method, validating the accuracy of the improved gust-front factor method for calculating equivalent wind loads on transmission towers under unsteady downburst effects. Verification results for different conversion standards, for tower types and, for heights demonstrate the broad applicability of the gust factor method improved.