Abstract: There are a lot of methods to measure the equivalent parameters of the crystal resonator. In engineering, the resonant frequency and the load resonant frequency are usually used to calculate the equivalent parameters. In this paper, the precise form of the resonant frequency, the load resonant frequency, the anti-resonant frequency and the load anti-resonant frequency are deduced, which serve as the basis to calculate the equivalent parameters of crystal resonators. Advanced design system (ADS) simulation show that this method is correct in theory. In this paper, the nonlinear equations are constructed by the derivative of the phase-frequency-curve at the point of resonance and anti-resonance to solve the problem of random walk of frequency in the experiment. Then, the two-dimensional search method is used to solve those nonlinear equations. The experimental results show that the equivalent parameters measured by this way are basically the same as those provided by manufacturer. This method does not adopt approximate calculation, namely, it is not only suitable for high Q crystal resonators, but also suited to low Q resonators. Therefore, it can also be applied to the field of sensors, such as temperature sensors, quartz crystal microbalances, and so forth.