The power loop of grid-forming new energy inverter based on droop control usually sets a lower cut-off frequency for the first-order low-pass filter to avoid output voltage amplitude and phase angle distortion. But the first-order low-pass filter is difficult to balance the filtering effect and dynamic characteristics of the power loop. Based on this problem, this paper firstly analyzes the influence of the first-order low-pass filter parameters on the output power characteristics of the grid-forming new energy inverter. Secondly, it proposes an optimization algorithm for instantaneous power filtering of the new energy inverter with variational mode decomposition. Finally, through simulation experiments, it is verified that the grid-forming new energy inverter has better dynamic characteristics of active power when it is added to the filtering algorithm proposed in this paper, compared with only using the first-order low-pass filter.