Effects of Gd purity on glass-forming ability (GFA) and magnetocaloric effect (MCE) of Gd52.5Co18.5Al29 amorphous alloy were investigated. It is shown that the impurities have an influence on the GFA of Gd52.5Co18.5Al29 glassy alloy rods and the maximum diameters decrease from 4 mm to 3 mm when the purity of Gd decreases from 99.94% to 99.2%. However, no decline of magnetocaloric effect is observed for different-purity alloys and the maximum magnetic entropy changes and relative cooling power of high-purity and low-purity Gd52.5Co18.5Al29 alloys are 9.4 J·kg-1·K-1, 8.1×102 J·kg-1 and 9.5 J·kg-1·K-1, 8.4×102 J·kg-1, respectively. Therefore, it indicates that lower cost Gd52.5Co18.5Al29 alloy prepared by commercial Gd is promising for further application as magnetic refrigerant