This paper proposes a method for high-precision detection of the current of a 270V high-voltage DC power supply. Based on the analysis of commonly used current detection methods, a high-end current acquisition design is proposed, which adopts the method of directly collecting current using operational amplifiers to achieve high-precision current detection. Voltage acquisition is achieved through a serial analog-to-digital converter, and the serial data results are outputted. Digital isolators are used to achieve electrical isolation and protection of the system. This method has high anti-interference ability and stability, suitable for monitoring the current of high-voltage DC power supplies. Experimental results show that the proposed method can achieve an accuracy of ±0.1% in the detection of current in a 270V high-voltage DC power supply, meeting the requirements of high-precision applications. This paper provides a reliable and high-precision solution for the detection of current in a 270V high-voltage DC power supply.