Considering the electromagnetic parasitic parameters of the encapsulated tube shell and layout, thepassband of an RF surface acoustic wave (SAW) filter narrows, and the standing wave increases. This paper proposesa method to quickly extract the electromagnetic parasitic effects in the package shell and layout and accuratelysimulate their influence on filter performance. First, FEM electromagnetic simulation software was used to extractthe electromagnetic parasitic parameters of the encapsulated tube shell. Then, circuit simulation software was employedto co-simulate the designed filter with the extracted packaging parasitic parameters and filter layout. This approacheliminates the need for repeated electromagnetic simulations in FEM software, improving time efficiency.The method was verified on a SAW filter with a center frequency of 1 268 MHz, a passband insertion loss of lessthan 1 dB, an in-band standing wave of less than 1.6, an in-band fluctuation of 0.5 dB, and a bandwidth of 24 MHz(relative bandwidth of 1.8%). The SAW resonators used in this design were de-embedded, allowing for more accuratesimulation of the measured filter results.