Er^(3+)-doped fluoride lanthanum aluminosilicate glasses with compositions of (65-x/2)SiO_(2).(25-x/2)Al_(2)O_(3).xAlF_(3).9.1La_(2)O_(3).0.6Er_(2)O_(3).0.3Yb_(2)O_(3) (x = 4, 8, 12, 20, 30) (mol%) were prepared and their glass transitiontemperatures and spectroscopic properties were investigated. The Ω_(2), Ω_(4), and Ω_(6) intensity parameters of glasses were calculated by Judd-Ofelt theory from absorption curves. It was found that glasses transition temperature and melting temperature decreased with the increase of fluoride content in glass, Ω_(2) decreased gradually with the increase of AlF_(3) content, but both Ω_(4) and Ω_(6) did not increase until AlF_(3) content increased to 30 mol%. The quantum efficiency of ^(4)I_(13/2) to ^(4)I_(15/2) transition of Er^(3+) ions increases with the increase of AlF_(3) content in glass. Fluorescent lifetime is longer in glass containing more AlF_(3) content.