A second-level liquid slag cache system with flow and temperature monitoring and control functions is disclosed. A slag inlet is located at an upper portion of the slag ladle casing; at least one slag discharging unit is located at a side of a lower portion of the slag ladle casing; one slag discharging unit is corresponding to one stopper; the stopper includes a stopper head, a stopper rod and a stopper control mechanism; the stopper control mechanism is configured to control the flow area between the stopper head and the sizing nozzle; a sealing cover is disposed outside the sizing nozzle; a slag control tube is installed at a bottom of the sealing cover. The present invention is able to achieve liquid slag buffer, flow control and heat compensation, so as to allow liquid slag to continuously stably perform a subsequent granulation process.