Using behavioral models to perform system simulation at behavioral level is currently a popular solution to verify mixed-signal systems. However, most of existing approaches only deal with ideal environments or make unrealistic assumptions, which cannot accurately evaluate the performance under supply voltage variation. In this paper, an efficient modeling approach with the effects of supply voltage variation is presented for PLL circuits to build accurate behavioral models in a short time using bottom-up extraction. Only three post-layout simulations are enough to generate accurate behavioral models under different supply voltages. The experimental results have shown that this approach can really have accurate responses under different supply voltages without time-consuming correlation analysis.