This paper takes a 4 mm-thick A7N01 aluminum alloy sheet as the research object and conducts simulations based on the laser-arc hybrid welding parameters of A7N01 aluminum alloy. Numerical simulations were performed using Fluent software to analyze the temperature field distribution and fluidity of the molten pool under different welding parameters, and to investigate how laser power and welding speed affect laser–arc hybrid welding. The results show that with the increase of laser power, the depth of the molten pool increases significantly. Meanwhile, the accelerated fluid flow speed inside the molten pool may enhance its instability. Although a higher welding speed can stabilize the molten pool in a shorter time, it is accompanied by a faster temperature change rate, which may lead to uneven cooling and the risk of cracking. On the contrary, a lower welding speed increases the heat input, resulting in a larger temperature gradient of the molten pool, which is conducive to forming a larger molten pool and deeper penetration. However, excessive heat input may also cause a series of welding defect problems.