The numerical simulation and investigation of lead-free Cs2TiBr6 perovskite based high efficiency solar cells (PSCs) is reported by using solar cell capacitance simulator-1D (SCAPS-1D). In the present work, the material optimization of different holes transport layer (HTL) and defect density of absorber layer are accomplished. The optimum thicknesses of HTL and absorber’s defect density are obtained as 10 nm and as 1×1013 cm-3, respectively. Among various materials, for most suitable HTL is MoO3 while TiO2 is taken as electron transport layer (ETL). Finally, the optimized structure for lead-free PSC consisting of TiO2/Cs2TiBr6/MoO3 results the highest power conversion efficiency (PCE) of 20.33% with VOC of 1.45 V, JSC of 15.38 mA/cm2 and FF is 91.01%. Thus, the lead-free inorganic Cs2TiBr6 perovskite provides an exciting alternative for fabrication of high efficiency and environment friendly solar cells.