The paper presents a method for investigating the bending stress at the critical section of “Asymmetric Involute spur Gear”. The method, ISO/TC- 60 has been used to theoretically calculate bending stress at the critical section of this Gear. The determination of the tooth form factor, stress concentration factor, critical section parameters and contact ratio has been accomplished for each set of gear. The gears with different pressure angle have been modelled by using “CATIA V-5 R15”software.The results obtained by theoretical method have been verified by using “ANSYS 12.0 software”. The comparative analysis of bending stress at critical section has been carried out.