The invention discloses a finite-element-based crankshaft stress analysis method. The problem that in the prior art, analysis of a crankshaft is not suitable for an enterprise is solved. The method has the advantages of being high in practicability, high in accuracy and capable of verifying the fatigue strength of the crankshaft through static analysis. According to the technical scheme, a crankshaft three-dimensional model is established; a crankshaft belt oil hole single-throw model, a crankshaft single-throw simplified model and a crankshaft integral model serve as static analysis models, and static analysis is conducted on the crankshaft; the three models are compared and analyzed, and the optimal model is selected; the crankshaft is subjected to kinetic analysis; a crankshaft modal test is carried out, and an analysis result is checked; the crankshaft is optimized, and post-optimization crankshaft static analysis and kinetic analysis are carried out.