Overall framework of Flow4DGS-SLAM. Given input RGB-D video, we first extract the prior semantic mask and optical flow, and feed them into a camera-induced motion decomposition module to filter out category-agnostic motion mask and solve an optical-flow guided camera initialization. The static gaussians help refine the camera pose during tracking, and the dynamic Gaussians are represented in a hybrid form, combined with a scene flow Gaussian propagation module and an adaptive gaussian insertion module to accelerate training.