Long-LRM is a model designed for 3D Gaussian reconstruction, capable of recreating large scenes from a series of input images. The model can process 32 images at a resolution of 960x540 in just 1.3 seconds, operating on a single A100 80G GPU. It integrates the latest Mamba2 modules with traditional transformer modules to enhance efficiency without compromising quality through effective token merging and Gaussian trimming. Unlike traditional feedforward models that can only reconstruct small portions of a scene, Long-LRM can regenerate the entire scene in one go. On large-scale scene datasets like DL3DV-140 and Tanks and Temples, Long-LRM's performance is comparable to optimization-based methods while achieving two orders of magnitude greater efficiency.