The invention relates to a device for detecting starting velocity of cut tobacco in the process pneumatic transmission and a method thereof. The device comprises a rectangular transmission pipeline, an air-material separator and a negative pressure gas source. The device is characterized in that the rectangular transmission pipeline is made of transparent materials; a top cover of the rectangular transmission pipeline is a structure which can move up and down parallelly to realize pipeline variable diameter; a wind speed knotmeter is arranged in the rectangular transmission pipeline; and the device also comprises a camera used for shooting the motion state of the cut tobacco in the pipeline. The invention is characterized in that the transmission pipeline part is processed by the transparent materials, thus being convenient for observing and testing; and the fast camera and the wind speed knotmeter are used for capturing the starting process moment of the cut tobacco and obtaining a wind speed signal synchronously. The invention inspects the starting speed by testing the starting process of the cut tobacco in the process of horizontal pipe pneumatic transmission, provides means for detecting the essential physical properties of the cut tobacco and provides the basis for studying various cut tobacco flow qualities and obtaining related basic data.