The invention discloses a safe and energy-saving control device and a control method of a hot rolling high-pressure descaling system, and relates to workpiece surface treatment equipment which is specially arranged and mounted in a rolling mill or is specially connected with a metal rolling mill for use. The safe and energy-saving control device comprises an operation control unit, a variable frequency pump operation state signal unit, a variable frequency giving unit and a variable frequency motor driving unit, wherein a pressure detection unit is connected with the operation control unit to feed back system pressure to the operation control unit; feedback control is performed on the rotation speed of the variable frequency pump through the variable frequency giving unit and the variable frequency motor driving unit to form a constant pressure control master control loop; a steel blank tracking signal is acquired through a steel blank tracking signal unit to perform feed-forward correction on the rotation speed of the variable frequency pump to form a variable flow energy-saving control auxiliary loop; operation control unit programmable control is formed by a CPU (Central Processing Unit) and a PLC (Programmable Logic Controller) to perform accurate control over the operation of a descaling water pump motor of the high-pressure descaling system; and the power consumption of the descaling system during operation is reduced on the premise of guaranteeing that water outlet of the system meets the technological requirement of descaling of the system.