The effect of starting notch machining methods on fracture splitting of connecting rod was studied by axial tensile tests with single edge notch. The axial tensile specimens were made of the high carbon microalloyed steel (C70S6) which is now most widely used by the connecting rod of fracture splitting. The single edge notch of axial tensile specimens were respectively machined by laser notch、wire cut electrical discharge and broaching. The notch tip plastic deformation of specimens was compared by the fractography. The experimental results indicate that the specimens with laser notch can be fractured by the smallest axial tensile load which is respectively about 20% and 30% smaller than the fracture load of the specimens by wire cut electrical discharge and broaching. Considering the rich micro-local crack transformation hardened zones around the notch by laser the paper present the equivalent critical stress intensity factor KIcL which can be used to calculate the fracture load with laser notch.