The current in Cloud-to-Groud (CG) flash return strokes is an important feature of lightning. It’s important for improving the technology of lightning protection. Nowadays more and more data are obtained by many observing methods, including short towers, tall towers, triggered-lightning and far field-current relations. It indicates that the mean of negative first return stroke currents is 30kA, the mean of negative subsequent return stroke currents is 12kA. And the mean of positive first return stroke currents is 35kA, the value of that sometimes can be hundreds. There are some differences for the mean of return stroke currents in different regions. Measurement using short towers or tall towers is the dominating method for the direct measurement of lightning currents. Both peak values and wave shapes are different at different height. The measurements of the subsequent return stroke current for nature-lightning and triggered-lightning are similar. The indirect estimation is more and more important with the development of lightning return strokes models.