The three step implicit Adams method which has higher accuracy and lager absolute stability region is proposed to improve now existing damper winding current calculation (one step forward difference method). Also, the effect of initial value setting and sampling frequency to algorithm is analyzed. Results show that improved method has better performance on tracking damper winding current of synchronous generator. By calculating damper current of synchronous generator in IEEE first bench case for SSR in PSCAD with simulation and comparison, advantage of the three step implicit Adams method is testified.