Camshaft of internal combustion engine

The invention discloses a camshaft of an internal combustion engine. The camshaft of the internal combustion engine comprises driving ends, bearing journals, standard shaft sections and a plurality of cams arranged between the bearing journals. The bearing journals and the cams are connected through weak shaft sections, the cams are connected through weak shaft sections, and the closer the weak shaft sections are to the driving ends, the larger the diameters of the sections of the weak shaft sections are. The diameters of the sections of the weak shaft sections, closer to the driving ends, of the camshaft of the internal combustion engine are larger, the main weak shaft sections are designed to be in conical transition connection to correspondingly improve the safety factor of a dangerous section, so that the strength and stiffness of the whole camshaft are improved, and the fault that the camshaft of the internal combustion engine is broken is avoided.