The homogeneously doped single crystal of ErxY1-xAl3 (603)4 in centimeter order was grown with flux mathod. The absorption and excitation spectra were measured. The oscillator gtrengths of eleven trasition bands and intensity parameters of Er ion were calculated by Jndd-Ofelt theory. From these results the Einstain spontaneous radiative emission cross-sections of different transitions were obtained. With these parameters the possible lasing transitions in EYAS crystal are discussed.