Ca2−xAl2SiO7:xEu3+ (0.03 ≤ x ≤ 0.21) and Sr2−xAl2SiO7:xEu3+ (0.03 ≤ x ≤ 0.15) phosphors are effectively excited by near-UV light (396 nm). The host composition and Eu3+ concentration of the two series phosphors substantially affect its emission characteristics. The calcium aluminosilicate Ca1.82Al2SiO7:0.18Eu3+ is 377% higher in red emission intensity than the Ca1.97Al2SiO7:0.03Eu3+, whereas the strontium aluminosilicate Sr1.88Al2SiO7:0.12Eu3+ is 343% higher in red emission intensity than the Sr1.97Al2SiO7:0.03Eu3+. In addition, the Eu3+ concentration of the Sr2−xAl2SiO7:xEu3+ (x = 0.12) showing the highest red emission intensity is much lower than that of the Ca2−xAl2SiO7:xEu3+ (x = 0.18). In spite of the low Eu3+ concentration, the red emission intensity and red color purity of Sr1.88Al2SiO7:0.12Eu3+ are much stronger and higher than those of the Ca1.82Al2SiO7:0.18Eu3+. Of the prepared phosphors, Sr1.88Al2SiO7:0.12Eu3+ is the optimal composition for obtaining strong and pure red light. Strontium aluminosilicate Sr2−xAl2SiO7:xEu3+ has distinct advantages including strong emission intensity, high color purity, and cost effectiveness.