According to the biological data of 1146 snails R . borneensis which were collected every month f rom May 2001 to May 2002, their biological observation data were comprehensively analyzed in the open country . The resulst indicate that this kind of snail Retusa borneensis , is of quantitative superiority in interval region of tidal zone with distinctive difference in vertical distribution. Preferring sun light, it always appears and disappears at the surface of arid sea-tidal flat. It s habitats are regulated by the distribution of tidal, sunshine and bait. It is evident collective reproduction w ith breeding period from May to September. Especially it teems in June and July and lives only one year and dies after reproduction. The young snails first appear at the late June. It s growth rate reaches the peak during July to September and April to June of next year. From November to January of next year, it almost stops growing. It is the stoutandest and strongest in the July of next year. The height and the width of the snails are linear interrelated, with equation: B = 0. 3224+ 0. 4916H ( r = 0. 9770) . The height of the snails and their fresh and dry weight are functional related, with equation: Wwet= 2. 1 @ 10 - 4 L2. 8352( r = 0. 8448) , Wdry= 2. 97 @ 10- 4L 2. 2803( r = 0. 8939) . In the end, the matter of the opportune moment to kill the snails is also discussed.