SnS was deposited on the surface of FTO/TiO2 electrodes with different molar concentration ratio of Sn2+ and S2- using successive ionic layer absorption and reaction (SILAR) method. Afterwards, the as-prepared TiO2/SnS composite electrode was assembled into a multilayer heterojunction solar cell with an architecture of FTO/TiO2/SnS/P3HT:PCBM/Ag. The TiO2/SnS composite films were characterized by scanning electron microscopy (SEM), Raman spectra analysis and Glow discharge optical emission spectrometer (GD-OES). The photovoltaic performance of solar cells were determined using UV-Vis spectra and I-V curves. Results showed that incorporation of SnS significantly improved the short-circuit current of the multilayer heterojunction solar cells. Meanwhile, the dependence of the photovoltaic performance of solar cells on the molar concentration ratio of Sn2+/S2- was investigated systematically. During the SILAR processes, a series of electrodes were prepared in the precusor solutions with different Sn2+/S2- molar concentration ratios (n(Sn2+):n(S2-)=1:1, 1:1.25, 1:1.5, 1:1.75 and 1:2). Moreover, GD-OES method distinguished the effects of Sn2+/S2- ratio on the SnSx layer deposition. It was found that the Sn2+/S2- ratio of SILAR precursors, dominated by thickness and chemical composition of SnSx, affected photovoltaic performance of the solar cells significantly. I-V test results testified that the ratio of Sn2+/S2- molar concentration was optimized at 1:1.5, which resulted in the highest photoelectric conversion efficiency. The open-circuit voltage (V-infinity), short-circuit current density (J(sc)), fill factor (FF), and power conversion efficiency (PCE) reached 0.373 V, 1.92 mA/cm(2), 51.2%, and 0.369%, respectively.