Abstract: The laser longitudinal mode-split technology provides a powerful tool to study the power tuning property for a laser with various frequency spacing form a few tens of megahertz to half of the longitudinal mode spacing.A serious of experiments have been done.The experimental results show that the power varying trend of o-light and e-light are opposite to each other,no matter what kind of Ne(Ne20 or the mixture of Ne20 and Ne22) is used and how much the mode split is.