Bonneville power administration（BPA）and power system analysis software package（PSASP）are two commonly used software programs for calculating short-circuit currents in China（the usage rate is higher than80%）.However，their calculation results are greatly different from the same source data，a fact that is affecting the decision-making of grid dispatching.By referring to current domestic short-circuit current calculation standards，it has been found that the main cause of the difference in calculation results of short-circuit currents between the two software packages under the power flow and network conditions is the lack of unified standards.Another important cause is inappropriate handling of the load model.Conclusions drawn from the analysis are valuable for standardizing short-circuit current calculation for inter-connected grids.