The laser welding with pre-melting liquid filler is developed to solve the problems, such as the reflection of incident laser energy by filler wire, and unstable keyhole in the process of laser welding with filler wire. The melting and filling characteristics of aluminum alloy filler material about laser welding with premelting liquid filler and filler wire are comparatively investigated. The results show that, in laser welding with pre-melting liquid filler, the filler wire is melt by arc, the filling stage is continuous and stable due to liquid metal wire relying on the guide role of the solid-state wire on the bottom inflow to the weld pool. It reduces the reflection of incident laser welding energy. Compared with laser welding with filler wire, the liquid filling material is far from keyhole edge so that it avoids the direct impact of fill material to the keyhole and the molten pool has a big size for the escape of bubbles. So it will help reducing the aluminum porosity. Stability of keyhole is improved in high speed welding. And it significantly improves the adaptability about the high-speed welding and wire feeding accuracy.