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The dislocations and the strength of a nickel bicrystal are investigated in present study. There are three kinds of crystalline orientations of the nickel bicrystal, namely (100), (110), and (111). Misfit dislocations are presented on the interface between two nickel grains when a compression process is utilized on the bicrystal. The misfit dislocations on a Ni(100) interface form a square-latticed network and those on a Ni(111) form a triangle-latticed network. When a large twist angle is applied to the Ni bicrystal, the square- and triangle-latticed unit of the misfit dislocation networks will shrink or even disappear. Thus, a plane defects distribute over the interface. If the bicrystal is compressed further, dislocations within each grain are developed from the defects on the interface between grains. The configuration of the dislocations within grains is more regular when the applied twist angle is smaller. A Ni(111) bicrystal owns the largest amount of maximal stress no matter what the twist angle is. Those of a Ni(110) bicrystal is the second and of a Ni(100) bicrystal is the smallest. [ABSTRACT FROM AUTHOR]