In this article, high-voltage (HV) electrostatic discharge (ESD) protection devices with high robustness and strong radiation tolerance are investigated by technology computer-aided design (TCAD) simulations and transmission line pulse (TLP) measurements. The TLP measurement results of laterally diffused MOS (LDMOS)-silicon-controlled rectifier (SCR) fabricated in $0.35 \mu \text{m}$ bipolar-CMOS-DMOS (BCD) process demonstrated that its ESD robustness is elevated by 58% than that of LDMOS and is up to 13 kV human body model protection level. Meanwhile, high holding voltage and current of 17 V and 1.8 A are achieved by low-voltage MOS (LV-MOS) cascade technology in LDMOS-SCR. TLP ${I}$ – ${V}$ curves and transient voltage waveforms exhibit high operational stability of LDMOS-SCR. Gamma-ray irradiation experiments show strong radiation tolerance of LDMOS-SCR, whose ESD performance had almost no degradation under total ionizing dose (TID) radiation of 200 krad(Si), while the failure current of LDMOS decreased by 2 A. Therefore, a properly designed LDMOS-SCR is an excellent ESD protection device for HV circuits, especially in space applications.