A power-integrated monolithic DC-DC converter is realized by using current-mode, voltage-mode dual-loop control architecture as well as the key technologies such as peak current sampling. Designed peak current sampling and slope compensation improve the system stability greatly, and improve the fast transient response capability of system. Aiming at the high-voltage module circuits such as high-voltage Low Dropout regulator(LDO), current sampling, the DC-DC converter increases high-voltage LDO radiation-hardening capability by using Zener diode, by replacing high-voltage thick-gate MOSFET with N-channel Junction Field-Effect Transistor(NJFET), and by reducing the number of high-voltage devices on the whole. The high-efficiency monolithic converter with input voltage of 5.5-17 V, voltage regulation of less than 10 mV, current regulation of less than 25 mV, output current of greater than 5 A, system quiescent current of less than 25 mA, maximum operating efficiency of 93% and total dose of more than 1×105 rad(Si) is developed in 30 V BCD(Bipolar-CMOS-DMOS)-based process technology, compared with radiation-hardening layout for special devices.