Song, Y. Liu, G. Xuan, K. JACoW Geneva, Switzerland 978-3-95450-182-3 10.18429/JACoW-IPAC2017-TUPIK063 English 1836-1838 TUPIK063 Contribution to a conference proceedings 2017 2017-05 http://dx.doi.org/10.18429/JACoW-IPAC2017-TUPIK063 http://jacow.org/ipac2017/papers/tupik063.pdf The interlock system is an essential component for an accelerator facility. A configurable software interlock system(SIS) is designed for Hefei Light Source II (HLS-II), which complements the hardware interlock system to ensure equipment and operators' safety. The system is developed using Python under the EPICS framework with the method of separating the configuration file from the interlock program. The interlock logic is completely determined by the configuration file and its nested tree structure is easy to expand. The test results indicate that the new software interlock system is reliable, flexible and convenient to operate. This paper will describe the design and the construction of HLS-II SIS.