This paper presents design parameter calculation methodology and its realization to construction for the 10/350${mu}s$ lightning impulse current generator(ICG) modelled as double exponential function waveform with characteristic parameters ${alpha},{eta}$. Matlab internal function, "fzero" was applied to find ${lambda}={alpha}/{eta}$ which is solution of nonlinear equation linearly related with two wave parameter $T_1$ and $T_2$. The calculation results for 10/350${mu}s$ lightning impulse current show very good accuracy with error less 0.03%. Two type of 10/350${mu}s$ ICGs based on the calculated design circuit parameters were fabricated by considering the load variation. One is applicable to the MOV based Surge protective device(SPD) for less 15 kA and the other is to test small resistive devices such as spark gap arrester and bonding device with maximum current capability 30 kA. The tested waveforms show error within 10% in comparison with the designed estimation and the waveform tolerance recommended in the IEC 61643-1 and IEC 60060-1.