The aim of the study is to design, analyse and carry out a topology optimization of a connecting rod for single cylinder four stroke petrol engines. In order to obtain a 3D CAD model from existing physical connecting rod is developed through reverse engineering. A three dimensional CAD model of a connecting rod has been created using SOLIDWORKS and it is imported to ANSYS for the coupled steady-state thermal structural analysis, to verify the design of a connecting rod before and after weight reduction. For material optimization, three different aluminium alloy materials such as ADC12, LM6 and Al 6061–T6 alloy were used. From the results obtained from coupled steady-state thermal structural analysis and topology optimization, the optimized design of a connecting rod of Al 6061-T6 alloy shows the von-mises stress of 33.17 MPa, factor of safety 8.32 and total deformation 45.023 mm as compared to other two materials. Based on the topology optimization methodology, it is noted that Al 6061- T6 connecting rod material reduced the weight up to 7.98 % as compared with ADC12 without compromising the strength to weight ratio and ductility.