The longissimus muscle from chilled beef was used as raw material to preliminary study the purification and characteristics of metmyoglobin reductase. The effect of temperature, pH and metal ions on the metmyoglobin reductase activity was investigated. Results revealed that the metmyoglobin reductase of longissimus muscle could be crudely purified with ammonium sulfate (65% saturation) and ultrafiltration (>50 kDa). SDS-PAGE analysis showed that the molecular weight of the metmyoglobin reductase of longissimus muscle was 29.0~66.4 kDa, mainly. The proper temperature of the metmyoglobin reductase of longissimus muscle was 40 ℃, with the proper pH 6.0. Cu²⁺ could inhibit the activity of the metmyoglobin reductase obviously.