This paper describes a fast and accurate nan-ampere current measurement method for mass production shipping stage testing, and its engineering evaluation of measured data variation with different conditions. The proposed method employs the IV conversion and the DC-AC conversion to suppress the low frequency noise effects and to enable multi-channel measurement. We have obtained the statistics of the measurement data with several sampling frequencies, moving averaging processing, several numbers of data and two source resistors, and its results show that the current as low as 0.02pA can be measured with good linearity and testing time of several tens of milli seconds.