Abstract: In order to find the optimum CaCl2 concentration and study effects of CaCl2 on seed germination characteristics under simulated acid rain stress, Festuca arundinacea seeds were treated with different concentration CaCl2 solutions and the related germination indexes were measured after seed soaking. The results indicated that seed germination percentage, germination energy, germination index, vigor index, seedling height, root length and seedling fresh weight increased firstly, and then declined with increaseing CaCl2 concentrations continually, while electrical conductivity of seedlings was oppsite, declined firstly and then increased. The results obtained from the comprehensive evaluation of principal component and subordinate function analysis showed that the order (from strong to weak) of effects promoted by Ca2+ was 50, 25, 10, 100, 5 and 0 mmolL-1. The 50 mmolL-1 CaCl2 solution soaking seeds was the best for F.arundinacea to improve the resistance to acid rain at the germination phase.