We have simulated and optimized a conductive cooling structure including the distribution of temperature in active layer, and the deformation of laser to achieve high power operation with low SMILE value. Unlike the traditional conductive cooling structure, our structure improves the heat dissipation efficiency from three aspects: with angle structure in the front of heat sink; double side heat dissipation and without submount packaging technology. In this report, an output power of more than 250W CW from a 4 mm long laser bar with a filling factor of 50% is shown at 240A driving current with a power conversion efficiency of 65%. The thermal rollover of this packaging conductive cooling device can reach 385W at 400A driving current. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.