Abstract: The spatial impulse response method has typically been used as the 'gold standard' to simulate transient acoustic field due to its excellent accuracy in the linear domain. To ensure the accuracy, a high sampling frequency was used which results in a large amount of data being processed, in order to improve time-consuming, a fast algorithm for impulse response calculation was proposed based on the impulse response between observed point and the projected point, and the critical parameters select were analyzed, the result verifies 1000 MHz as calculation sampling frequency and 500 MHz as interpolation sampling frequency is a better choice. This method can improve the computation efficiency 18 times than the direct solving.