In recent years, horizontal wells technology is widely used in the development of the heterogeneous reservoirs. The horizontal wells model at the heterogeneous bottom water reservoir is established and the numerical simulation technology is used to study howthe plane and vertical heterogeneity of the reservoir （different permeability differential and high permeability width） can influence the water flooding lawin the horizontal wells. The study result shows that reservoir heterogeneitycan affectwater breakthrough position and average crude output in the high permeability zone. The research has importance in guiding the exploitation of the heterogeneous bottomwater reservoir.