Abstract: Instrumentation is one of the important techniques in the software testing. When instrumentation was applied in the flight-control software testing, the real-time performance of the original software becomes bad even lead to failure of the software, due to the extra spending on the instrumentations. In view of this problem, a new instrumentation method which is based on the BOOL array used to storage the code information was presented. Compared with traditional methods, this new method not only optimizes the instrumentation contents but also reduces the real-time influence of the instrumentation on the original software. A simulation test platform was been set up and a certain type of flight control software was used as the test object. Then, plenty of experiments have been done to demonstrate the effect of the new instrumentation method. The result show that the method greatly reduces the run time of the instrumented program which to ensure the real-time requirements of the flight-control software.