The crankshaft of a four-cylinder internal combustion engine was taken as the research object, the whole crankshaft beam-element FE method to calculate crankshaft bearing load and crankshaft deformation of multi-cylinder internal combustion engine was studied. This method is closer to the practice and could calculate all main bearing load compared with the traditional ones in calculating crankshaft bearing load of multi-cylinder internal combustion engine, and it is a simple, convenient, save-time method used in calculating crankshaft deformation compared to whole crankshaft solid-element method and its calculating precision could meet the requirements.