Using 41°Y-X LiNbO3 as substrate material, selecting the double T-type impedance element structure, and adopting the water level packaging technology, a miniaturized WLP packaged SAW filter with relative bandwidth of 5.8%, minimum insertion loss of -2.8 dB and volume of 1.1 mm×0.9 mm×0.5 mm is fabricated. A special probe card is developed to complete the test of the packaged wafer on-line. The test results show that the test results of the probe card are in good agreement with that of the wafer assembled into the actual circuit, which solves the test problem of WLP packaged SAW filter.