Abstract: Wet fermented protein feed of maize product with sealed package that was fermented by probiotic bacteria after yeast fermentation and alcohol extraction.Because it had good solubility,strong digestion and absorption abilities,rich and high-quality protein,the growth speed of beef cattle was fast when it was used in the fattening of beef cattle.The slaughter rate of 15 fattening cattle from 2 breeding farms that was fed with wet fermented protein feed was compared with that of 425 fattening cattle from 24 breeding farms that was mot fed with wet fermented protein feed.It was shown that the slaughter rate of beef cattle showed highly positive correlation with the slaughter weight（R2=0.952 8）.And the slaughter rate of fattening cattle that was fed with wet fermented protein feed in the whole test period was 3.65 percentage points higher than that of fattening cattle that was fed with conventional feed,and thus the income for each cattle increased 640 yuan.Therefore,the economic benefit of the beef cattle＇s fattening was significantly enhanced by feeding with wet fermented protein feed.