The invention discloses a mechanical ultrasonic type bagasse leaching device with a feeding trough and a pulper. The bagasse feeding trough is arranged above a body of a leaching device; three stages of contra-rotating cosine rollers are arranged in the body; surfaces of the contra-rotating cosine rollers are continuous cosine curved surfaces; a bagasse guide groove is formed below each stage of contra-rotating cosine roller; the final stage of guide groove is connected with a hopper of a bagasse elevator; a discharging groove of the elevator is connected with a temporary storage groove via a cascaded pulper; a water inlet valve is arranged on the elevator; a filter and a liquid outlet tube are arranged on the upper part of the body; and a mechanical ultrasonic exciter is arranged at the left lower corner of the body. The three stages of contra-rotating cosine rollers and the mechanical ultrasonic exciter have distinct characteristics, and can cooperatively facilitate leaching and extracting of sugar, and the mechanical ultrasonic type bagasse leaching device has working principles and technical effects which are difficultly predicted by those skilled in the art, and has high actual application value.