Abstract：To analyze the abnormal behavior of program induced by software defects, a characterization method of program behavior was proposed firstly, and then the baseline behavior and fault behavior of program got defined and formally described. A quantitative approach to represent the fault behavior of program was proposed afterwards. Furthermore, a Program Fault Behavior Analysis (PFBA) was delivered and implemented, which selected system-call as state granularity of program behavior. Based on specific embedded benchmarks, the experiment was followed through with fault injection method to obtain early-described indices of fault behavior. The experimental results show that there exists a difference among program behaviors under each individual fault type. Based on an in-depth analysis, it is demonstrated that the diversity of fault behaviors is induced by algorithm implementations and structural characteristics of embedded program themselves. Therefore, the analysis of fault behavior presented here can reveal the characteristics of embedded program response behavior under specific software defects, as well as providing important feedback to the process of program development.