Plastic deformation is accompanied by the conversion of mechanical energy into heat. The deformation heterogeneity related to the Portevin-Le Chatelier effect （PLC） in Al-Mg alloy during a tensile test at ambient temperature is investigated through temperature field measurement by infrared pyrometry. Under different applied strain rates, three types of stress-strain curves （types A—C） are obtained respectively. Correspondingly, the similarities and differences of temperature-strain curves are compared and interpreted qualitatively. And the spatial propagating characteristics of the three types of PLC deformation bands are observed and analyzed. The temperature rise on the surface of the specimen increases with the increase of strain rate. And the obliquity of PLC band changes either at the ends of the specimen or at the highest temperature area outside the band.