This study investigates the mean flow and radial heat-transfer behaviors in semi-closed rotating disk cavity within the canned reactor coolant pump. The flow in the semi-closed cavity contains the Stewartson type flow at inner region and the Batchelor type flow at outer region as well as the affected zone of discharge-hole. The mechanism of the radial heat-transfer is revealed that the non-direct discharge portion of superimposed flow is the carrier of heat transporting from outer periphery to discharge-hole. The effects of rotating Reynolds numbers, cavity aspect ratio and radial location of discharge-hole on the discharge ratio, pumping mass flow, local wall shear stress and radial heat-transfer coefficient are examined in the semi-closed rotating cavity flow, respectively. Based on the radial heat transfer behavior of pumping secondary flow, an equivalent thermal network is proposed and validated by experiments, which can effectively predict the radial temperature distribution from the discharge hole to periphery with the viscous-heating and non-isothermal effects.