The invention discloses a high-strength crankshaft of an engine. The crankshaft is made of non-quenched and tempered steel. The non-quenched and tempered steel comprises, by weight, 0.25-0.3% of C, 1.5-2.0% of Mn, 0.15-0.25% of Si, less than or equal to 0.015% of P, less than or equal to 0.05% of S, 0.03-0.1% of Cr and the balance Fe and inevitable impurities. According to the crankshaft, the C content is low, so that a crankshaft blank is easy to straighten, and the rejection rate of the crankshaft blank is decreased; the Mn content is high, so that the strength of the crankshaft material isimproved; rare metals Mo and V are not added, so that the steel cost is reduced; and the bending strength and the torsional strength of the crankshaft are greatly improved through the strengthening mode of carbonitriding (soft nitriding) and water quenching.