In a free-stall barn, free access to a ration depends on feed being within reach of cows. The objective of this study was to determine the change of ration form with eating behavior of cows in a free-stall barn. Twenty Holstein cows (average parity 3.2) were offered total mixed ration once daily at 1030 in a flat feed trough, through a self-locking feed barrier. From 1730 to 0530 the following day, the ration height was measured, without contact, at 10 cm intervals from the trough wall to 140 cm away (15 points) at 2 m intervals on the trough (6 lines), every 30 minutes. Eating behavior of cows was observed at 5 minutes interval, individually. Kruskal-Wallis analysis was used. The average ration height decreased linearly with cumulative eating time of cows. Over time, the position of the ration peak in the trough moved away from the trough wall: at 180 minutes, 70 - 80 cm; at 360 minutes, 80 - 90 cm; at 540 minutes, 90-100 cm. The changes of ration form were related to the eating behavior of cows. There were three time phases in the changes of ration form. In the first phase (within 90 minutes after the start of experiment), cows ate the ration in the close area to trough wall. And the residual ration accumulated in 70 - 100 cm distance position. In second phase (90-360 minutes after), the area where cow ate was expanded. The ration accumulated in this phase in 90 - 100 cm distance position. In third phase (360-720 minutes after), cows had eaten almost all ration closer than 80 cm position, and the height of ration in 90-100 cm position was not changed. For keeping the free access to ration, the pushing up operation had to be done before 0130 (540 minutes after).