The topic of the thesis is modifying part of keyword spotting that feature extracting, we substitute method Mel-frequency cepstral coefficients for method Linear prediction coefficients, and construct a voice-activated car by speech recognition. There are two topics in the thesis. In the first part, we focus on keyword spotting, and our keyword models and garbage models are building by sub-syllable models, and the advantage is that the system can save a lot of time. In the second part, we use Visual Basic 6 to make a human-machine interface for real-time recognition, and we combine the human-machine interface with remote control car to make a voice-activated car.