The increase of thermal load has brought severe challenges to the reliability of turbocharger turbine end and shaft-attached components and the high-temperature discoloration of rotating shaft and the coking of lubricating oil have become the main failure modes of turbocharger. The cavity of turbine shaft can block the heat transfer from turbine head to shaft. Numerical simulation methods were used to study the effects of different cavity diameters and shaft heat transfer coefficients at the position of floating bearing on stress and heat transfer characteristics of turbine. The results show that the shaft cavity decreases the stress of R fillet for turbine back disk, but increases the risk of low cycle fatigue failure. The larger cavity diameter will lead to the more obvious thermal resistance effect. Compared with the case without cavity, the heat transfer from turbine head to floating bearing at the turbine end reduces by 0.8%-4.4%, and the shaft maximum temperature adjacent to floating bearing at the turbine end decreases by 2.3-9.9 ℃.