The mainstream packaging for RF-SAW filters in the terminals are mainly used the flip chip technology based on LTCC ceramic board. The packaged standard size is 1.4 mm×1.1 mm for single SAW filter CSP. This paper introduces a CSP SAW filter based on multilayer print circuit board (PCB), and the size goes down to 1.4 mm×1.1 mm. With the usage of PCB board, the cost of single device will be cut more than 30%. Through optimizing the board structure, the coefficient of thermal expansion (CTE) of PCB board can match with that of its counterpart LiTaO3 and the moisture absorption is low. The post reliability test result shows that the RF SAW filter with the proposed structure can meet the requirements of engineering applications.