Abstract: By using implant test, cold cracking sensibility of 10Ni8CrMoV high strength steel was analysed.At four welding conditions of non-preheating, preheating at 100℃, preheating at 150℃ and preheating at 150℃ then postheating 200℃×2 h, the critical rupture stresses of implant test and the welding thermal cycling parameters were measured, and the fracture appearance were observed by scanning electron microscope.By all these, the welding cold crack sensibility of 10Ni8CrMoV steel was analysed comprehensively. The results showed that with the preheat temperature being increased, the critical ruptrue stresses of implant test are higher, and the areas of dimple are relatively increasing in fracture surfaces, and the rupture tendency is displayed from intergranular crack to transgranular crack to ductile rupture.10Ni8CrMoV steel possesses a high cold cracking sensibility.Preheat and postheat treatment technologies can obviously improve the weldability of 10Ni8CrMoV steel.