Abstract: At present, a commercial fiber laser welding of aluminum alloy at high welding speed is achieved at tens of kilowatts power level due to extremely high reflectivity of aluminum alloy at the near-infrared wavelength. In this work, high-speed welding of aluminum alloy was realized by using low-power (kilowatts power level) fiber laser combined with pressure. The influence of process parameters on the weld formation, the variation of energy convergence during laser pressure welding, and the microstructure characterization by using electron backscatter diffraction (EBSD) were investigated through both simulation and experiments. The results show that successful welding was achieved at laser power from 1 kW to 6 kW and welding speed from 5 m/min to 20 m/min. It is worth noting that successful welding was achieved even at 50 m/min when laser power was 6 kW. Simulation showed that laser pressure welding provided significant energy convergence, which resulted in the power density up to 4.6 times higher than the original focused laser beam, indicating an efficient usage of laser energy. Microstructure of the welds further proved that laser energy convergence led to rapid melting and solidification of the material, which subsequently eliminated the lap gap under pressure.