The invention discloses a high-voltage ESD (electro-static discharge) protective device triggered by a bidirectional substrate. The high-voltage ESD protective device triggered by the bidirectional substrate can be used for an on-chip IC (integrated circuit) ESD protective circuit and mainly comprises a substrate Psub, a high-voltage deep N trap, a lightly doped p-type drift region, a first highly doped N+ injection region, a first P+ injection region, a second N+ injection region, a second P+ injection region, a third N+ injection region, a third P+ injection region, a polycrystalline silicon grid, a grid thin oxide layer and a plurality of field oxide isolation regions. Reverse PN nodes at the interface part of the high-voltage N well or the N well and the substrate can be triggered and conducted through the forward and reverse ESD high-voltage pulse effect, two structures of internal SCR (silicon controlled rectifier) and LDMOS (laterally diffused metal oxide semiconductor) operate at the same time so as to form an ESD current discharge path to improve the secondary breakdown current of the device and lower the conducted resistance. The maintaining voltage of the device is improved through hoisting the channel length of the LDMOS device, the internal structure design as well as optimization of layout hierarchy, and the high-performance ESD protection is realized.