Based on quantum technologies to measure alternative current (AC) signal, sampling is the most commonly used method. In this method, the measurement accuracy of AC voltage amplitude depends mainly on measurement accuracy of differential signal. Therefore, in this paper, impact on measurement accuracy, quantum AC voltage steps, sample rate and window function, are analysed. Without transient process, it is observed that the relative error after compensation decreases with the increasing number of steps in case of sampling rate is constant. Similarity, when the steps of Quantum AC voltage remain the same, it shows that the relative error after compensation decreases with the increasing number of sampling rate. With transient process and noise interference, the measurement accuracy has been significantly improved by increasing the window function.