In order to study the issues of non-uniform performance of the emitters in laser bars, 960 nm laser bars with 38 emitters and cavity length of 2 mm packaged by the microchannel cooler were experimentally studied. The peak output power reaches 665.6 W, the electro-optic conversion efficiency is 63.8%, and the centroid wavelength is 959.5 nm under the driving current of 600 A and the duty ratio of 10%. Firstly, theoretical analysis was made to find out the relationship between the external stress and laser''s parameter changes. Then, the laser photoelectric characteristics parameters such as threshold current, slope efficiency, spectrum and optical power were measured via the test setup. From external stress theory, it is clear that external stress can significantly affect the laser''s parameter performance. Specifically, compressive strain will cause blue-shift in wavelength, decrease in threshold current, and increase in laser and slope efficiency; tensile strain by contrast, will have completely opposite effects on the laser performance. Studies have shown the performance that affects the internal emitters is not only thermal effects, but also residual strain after packaging. The distribution of stress can basically predict the pattern of array performance, which will provide a reference for the development of high peak power, high reliability semiconductor laser arrays.