PortraitGen is a multimodal generative prior-based tool for editing 2D portrait videos, capable of enhancing them to 4D Gaussian fields for multimodal portrait editing. The technology quickly generates and edits 3D portraits by tracking SMPL-X coefficients and utilizing a neural Gaussian texture mechanism. It also introduces an iterative dataset updating strategy and a multimodal face-aware editing module to improve expression quality while maintaining personalized facial structures.