A method for calculating current leakage effect of high voltage solar array in LEO was developed in this paper. This method is based on current balance, a simplified structure of solar array and an empirical model of current collection for solar array. Using this method, the relationships between power loss and plasma environment, solar array voltage, the area of solar array exposed conductor were analyzed in current leakage. The main results are concluded as follows. Firstly, the power loss of solar array in current leakage declines quickly with the increasing of orbital altitude. The most serious range for current leakage is region among 300～400 km of orbital altitude where the plasma density is high. Secondly, the power loss increases exponentially with the voltage of solar array. Meanwhile, is also noticed that the power loss is far less than 1% of total power when the voltage of solar array is below 200 V. Thirdly, the power loss increases linearly with the area of solar array exposed conductor. Accordingly, the current leakage effect can be reduced by decreasing the area of solar array exposed conductor.