The formation process of Taylor bubble caused by the heat leak in cryogenic tubes was investigated using the particle image velocimetry (PIV) technique and high speed camera. A correlation for Taylor bubble formation was developed with the consideration of turbulence suppression, tube inner diameter, fluid properties and inclination angle, etc. The predicted value of the position of Taylor bubble formation has a maximum error of ±7.9% compared with the experimental data in present study, and a maximum error of ±20% compared with the experimental data from the reference.