The self-developed hammering method experiment modal analysis system is introduced, which including software modules of the digital signal sampling and analyzing system（VTCL_DSP） and experiment modal analysis system(VTCL_MDT) self-developed and hardware modules of the NI-USB9215A signal collector, a three-dimensional acceleration sensor and computer etc. In this system, fixed acquisition time-length and varied-time-based technology is adopted for getting the signals of the three-vector response accelerations and impact force during the trigger process. The advantages of the method are discussed. This paper also introduces two application examples: a modal analysis for power-train of a SUV and a modal analysis for Body-in-White of a sports-car. The results have high accuracy and high stability. The system will push forward the technology of model test and analysis.