Abstract: At the beginning of the development in Iraq M Oilfield, drilling vertical well is the main method. In order to develop efficiently and low the investment cost, achieving the goal of "less wells with more production", the method of drilling horizontal well was adopted in later period. The reservoir characteristic in horizontal section is complicated with carbonatite, sandstone, and mixed clay and shale, which has negative effect on horizontal well completion. In order to select proper horizontal completion method, this article optimizes the horizontal well completion technology method through interval transit time and rock strength analysis as well as onsite application which finally enhance oil production, extend the life of well, lower the operation cost and bring the reference for similar oilfield development.