The peak prediction of short circuit current is very important for the realization of selective protection of low voltage system, and it is still lack of in-depth study. By using the early detection technology of short circuit fault, a simulation model of single phase short circuit fault for low voltage system is established. The phase angle of short-circuit fault current is obtained, and the characteristics of short circuit current peak under different phase angles are analyzed. Through the historical data of short circuit fault current, the prediction rule based on conditional cloud generator is constructed, and the peak prediction model of short circuit current based on two-dimensional cloud is established. The experimental results show that the prediction method of short circuit current two-dimensional cloud model can accurately predict the fault current, which can lay the foundation for the realization of low voltage selective protection technology. This work is supported by National Natural Science Foundation of China (No. 51377023).