In the fields of aerospace, medicine, transportation, and others where strict safety is paramount, MC/DC (modified condition/decision coverage) was commonly utilized instead of traditional coverage criteria in software testing. As a result, a greater number of high-quality test cases are necessary. Due to the aforementioned considerations, a white-box unit test case automatic generation scheme for MC/DC coverage was proposed. Based on the theoretical foundation of mapping from MC/DC coverage to branch coverage, the proposed scheme has developed several tools based on the framework of the symbolic execution engine KLEE and the LLVM(low-level virtual machine). With this approach, automated test cases can be generated that attain the highest possible MC/DC coverage, thereby assisting human testers in identifying potential code defects which prevent the achievement of 100% MC/DC coverage.