Al-Si-(Mg) alloys are used in the main carrier of wind turbines, which is often encountered particle erosion. This study is to explore the effect of friction stir processing (FSP) with artificial aging on erosion characteristics. The full-annealed A384 was used as base metal (BM). Si particles, τ1 (Al9FeNi), δ (Al3CuNi) and Q (Al5Cu2Mg8Si6) precipitate phases were observed in the A384 alloy. It generally had high erosion rate at oblique impact angles. After FSP, the refined and uniformly distributed second phases can help to increase the erosion resistance. The Si and δ phases were found with brittle fracturing at the end of erosion grooves. The τ1 phase was easily removed by the impact of erodent particles. It was inferred that Si and δ were beneficial, whereas τ1 phase was detrimental to the erosion resistance. The hardness and deformation resistance were increased, the maximum erosion rate was decreased after peak-aging treatments.