Since the Siam Photon Source (SPS) has electron beam energy upgraded from 1.0 GeV to 1.2 GeV in 2005, the storage ring impedance measurements was done once in 2007. Two insertion devices (IDs) have been installed in the SPS storage ring during June to August 2013. These add several vacuum components in the storage ring, which affect the ring impedance. The instabilities of beam inside the ring are not well understood and need further investigation. Quantitative understanding of instabilities requires detailed knowledge of impedance of the ring. For this purpose, the activities of impedance study are developed aiming to establish an impedance database. The wake potentials of each vacuum component will be kept and maintains in a standard format. The Self Describing Data Sets (SDDS) file format will be utilized torecord component's wake potentials. The wake potentials of each vacuum component can be obtained from a particle tracking simulations; CST particle studio will be used in the simulation process. Details of beam impedance study on tapered chambers, bellows, and small cross section chambers in order to construct an impedance database will be presented.