High power density as the critical performance of laser diode pumps significantly affects both efficiency and power of a solid state laser. In this report, we designed a new packaging structure that two laser bars bonded on the top and bottom of a MCC, respectively, to achieve higher power density at the same bias current or the same power density at a reduced bias current with respective to one laser bar on a MCC. We achieve 1KW output power at a lower bias current 450A with 2.3W/A slope efficiency from a dual-bar MCC at a duty cycle of 8% (200 μs/400 Hz). Other performances like spectral width broadening, wavelength shift and reliability about 1KW quasi-CW high power laser diodes and 5KW for one vertical stack with five dual-bar micro-channel coolers (MCCs) also are discussed. The reliability of dual-bar MCC packaging structure is also studied by life-time testing, and the output peak power of all devices degraded less than 5% after working for 1353 hours. © 2018 SPIE.