The liver responsible for 90% lipid synthesis in poultry thus plays important role in the growth of Muscovy duck, which obtains high-fat deposition ability in a time-dependent manner. Therefore, male Muscovy ducks at the age of 14, 28, 42, and 56 days were selected for body weight (BW), carcass weight (CW), subcutaneous fat thickness (SFT), abdominal fat weight (AFW), intramuscular fat content (IMF), breast muscle fiber (BMF) diameter and density determination. Two-dimensional electrophoresis (2-DE) combined with liquid chromatography linked to tandem mass spectrometry (LC-MS/MS) was used to analyze the differentially expressed proteins in the liver at each stage.