Abstract: Through analyzing issues existing in irrigation sprinkler test systems that were based on the PC's ISA bus, the authors proposed a new approach based on the distributional bus technology to automatically test rainfall distribution of irrigation sprinkler. By using the RS485/422 bus, a PLC module, which was installed in test field as a rainfall gathering module, and a PC composed an 1:n network for carrying out the data transmission. This approach expanded radial line up to 16, each line up to 1280 test points, so that the total number of test points was up to 20480. The monitoring software was developed by using VB6. This improved portability of the software, enhanced reliability, interoperability, and expansibility of the test system, and provided reliable data and an new analysis method for researchers to test and research new sprinklers.