This research at Sungai Lilin, South Sumatra Basin field with sandstones reservoir has been done. The geology analyst summarized that a good quality reservoir is in both Talang Akar and Baturaja Formations. Sungai Lilin field already has Seismic data and well log data as well. This research used the simultaneous inversion method and then LMR transformation. The target research focused on depth of 720 ms (772 m) until 860 ms (932 m) which is as an interest area to characterize the reservoir. The simultaneous inversion method yielded parameters of P impedance, S impedance and rock density. Afterwards, these 3 parameters were transformed to LMR. LMR analysis consists of Lambda-Rho and Mu-Rho which represent the incompressibility of pore fluid content and the rigidity of rocks, respectively. This research result shows that the potential reservoir is in pores of sandstone and limestone in Talang Akar Formation and Baturaja Formation.