The peripheral component interconnect ( PCI) bus, which is a high performance local bus of the computer, has in creased the capability of data transfer greatly. Most of the chips of PCI bus are not only expensive but also complicated in PCI configuration. CH361 chips have solved these problems. This paper introduces the design of hardware and software about data sampling based on PCI with the programs of data sampling and principle circuits of the hardware. This data sampling card works well in detecting the signal whose frequency is less than 100 kHz.