Many tree species in forest ecosystems have symbiotic relationships with ectomycorrhizal fungi (ECM), which protects their hosts from environmental stress. Effects of ECM on growth, elemental nutrients, and rhizosphere soil of Pinus massoniana seedlings under simulated acid rain were analyzed in this study to provide a scientific basis for restoration of P. massoniana in an area with severe acid rain in China. Two-year-old seedlings of P. massoniana were grown in forest soil from one of six treatments, including pH 5.6 (CK) inoculated with ECM, CK without ECM, pH 4.5 inoculated with ECM, pH 4.5 without ECM, pH 3.5 inoculated with ECM, and pH 3.5 without ECM. The results showed that:(1) For the P. massoniana seedlings grown in soil not inoculated with ECM, the acid rain treatments significantly reduced leaf area, total biomass, and biomass of roots, stems, and needles, whereas plant height did not differ from that of plants grown in CK. Inoculation with ECM removed the negative effects of acid rain on growth. (2) For the P. massoniana seedlings grown in soil without ECM, the N, P, and Ca content was higher in needles and decreased in roots in the acid rain treatments than those of plants grown in CK. The content of Mg decreased in needles in acid rain treatments, whereas it increased at first and then decreased in roots with a decrease in pH with respect to that of plants grown in CK. Inoculation with ECM significantly increased N, P, Ca, and Mg content of roots; however, there was no effect on N, P, Ca, and Mg content of the needles in the pH 3.5 treatment. (3) For plants grown in soil without ECM, pH 3.5 treatment decreased the content of soil organic matter, available P, available K, soluble carbon, soluble nitrogen, nitrate nitrogen, and ammonium nitrogen, but inoculation with ECM improved soil quality. Acid rain treatments did not significantly affect the cation exchange capacity. These results indicated that inoculation with ECM could stimulate growth of P. massoniana seedlings and effectively alleviate adverse effects on nutrients and rhizosphere soil of P. massoniana seedlings caused by acid rain. Therefore, inoculation with ECM could be an effective way to decrease the hazard of acid rain to Pinus massoniana.