In order to facilitate the collection of multi-channel signals that do not share the same ground and prevent crosstalk between signals, an isolation design is added on the basis of the collection circuit: isolated power supply, isolated optocoupler and digital isolation channel, which greatly reduces noise interference and improves the collection accuracy of the system . Based on the system circuit design, the working principles of the isolated power supply LTM8068 and the linear isolation optocoupler HCNR201 are analyzed, and the ROM table is established to realize the chip selection of the acquisition module and the switching of the analog switch channel, which facilitates control and improves the versatility of the acquisition board. The experiment verifies the sampling accuracy of the circuit by inputting a 0~5V analog quantity. After practical verification, the sampling accuracy of the isolated acquisition circuit is better than 2‰, and it has strong anti-interference ability, good circuit versatility, and strong practical value.