Introducing spiro-OMeTAD as protecting layer for CH3-NH3PbI3 in a liquid-type perovskite solar cell is found to suppress the degradation of the device efficiently. Evidenced by XRD analysis, the dissolution of CH3NH3PbI3 is significantly retarded in the presence of spiro-OMeTAD capping layer and consequently the current-voltage parameter decay is stabilized.