Abstract: The coupled mathematical thermal equilibrium model for main equipment in the spent fuel pool (SFP) is established and the transient change of the temperature of SFP water in various loss of coolant accidents is studied based on AP1000 power plant. The results show that the fuel rods are exposed after 24h when the loss of coolant accident occurs during the unloading of the whole reactor, while the fuel rods are exposed after 213h when the loss of coolant accident occurs after the fuel loading operation. The results give a reference response time for the operator to take countermeasures for the loss of coolant accident for the spent fuel pool.