PURPOSE: An oil press mill and an oil press plate are provided to improve the yielding percentage and the safety by improving the structure of the oil press mill. CONSTITUTION: A lower oil press plate contains many penetrating holes(30). An auxiliary oil press plate is installed on the lower oil press plate. A tunnel(36) is formed between the auxiliary oil press plate and the lower oil press plate to flow out oil. Support members are installed between the auxiliary oil press plate and the lower oil press plate for maintaining the shape of the thin auxiliary oil press plate. Thereby, the yielding percentage is improved by uniformly pressing an oil press mill and quickly flowing out the oil.