The invention relates to the technical field of direct-current sampling circuits, in particular to a direct-current high-voltage isolation sampling circuit which comprises buses to be sampled, an A/D (analog/digital) conversion circuit, an optical coupled isolation circuit and a signal processing unit. A voltage division sampling circuit is serially connected among the buses including positive buses and negative buses, an output end of the voltage division sampling circuit is connected with an input end of the A/D conversion circuit, an output end of the A/D conversion circuit is connected with an input end of an optical coupled isolator, and an output end of the optical coupled isolator is connected with the signal processing unit. Compared with the prior art, the direct-current high-voltage isolation sampling circuit has the advantages that signal processing links are few, and the sampling precision is improved; the A/D conversion precision is improved owing to the independent A/D conversion circuit; the direct-current high-voltage isolation sampling circuit is simplified, and the quantity of devices is lowered; and as signals are isolated, the requirement on an optical coupler is greatly lowered, and the cost of the direct-current high-voltage isolation sampling circuit is saved.