Abstract: Whether the log-dropout sorting system can be adopted or not by gravity for dropping out the logs eccentrically loading on toggles, it is of vital importance to its popularization and development. The theory of this system is discussed in this paper. It is verified by experiment and the formular for calculating the distance from the centre of log to centre Hne of the conveyor is given. Authors of this paper hold that all kinds of log can be successfully dropped themselves out along the ground when their centre of gravity is located inside the guide c (See Fig. 2).