Injection-locking technique is receiving increasing interest in industrial applications, which is especially suitable for smart antenna array, but relative experiments are complicated. The article focuses on the theory and experiment of the technique. Firstly, section 2 reviews the theory of injection-locking technique, and summarizes two useful conclusions on injection-locking bandwidth and phase difference adjusting bound of the phenomena. Secondly, section 3 describes experiments using commercial microwave integrated circuit (MMIC) voltage controlled oscillator (VCO), which is reduces the experimental conditions. Experiments results perform very well.