Bottom water coning is one of the important problems in the development process of horizontal wells in bottom water reservoir. To accurately predict the time of bottom water coning is vital for reasonable development of the bottom water reservoir. For the horizontal wells in bottom water reservoir with barrier，physical model was establish based on oil-water two phase flow theory and the law of fluid flow in porous media，and potential distribution of horizontal wells in bottom water reservoir was obtained through the mirror image and potential superposition principle. The formula for water breakthrough time of horizontal wells in bottom water reservoir with barrier was deduced. Case calculation shows that the relative error between the formula calculation results and the actual water breakthrough time is 5.39%. The existence of the barrier greatly delays the bottom water coning time，and the water breakthrough time increases with the increase of the barrier radius and water avoidance height. With decrease of horizontal section length and increases of daily oil production，the water breakthrough time of horizontal well decreases. The research has certain guiding significance for the design of the horizontal well length and water avoidance height and development of the bottom water reservoir with barrier reservoir.