A　novel　numerical　method,　referred　to　as　Lorentz　precise　integration　time-domain　(Lorentz-PITD)　method,　is　proposed　to　deal　with　the　scattering　problem　from　a　moving　conducting　slab.　Both　the　overset　grid　generation　technique　and　the　Lorentz　transformation　are　employed　in　this　method.　By　using　the　Lorentz　transformation　and　the　linear　interpolation　technique,　the　incident　plane　wave　in　the　rest　frame　is　introduced　to　the　moving　frame;　the　scattered　fields　are　transformed　from　the　moving　frame　to　the　rest　frame.　Numerical　experiments　validate　the　Lorentz-PITD　method　and　show　that　the　Lorentz-PITD　method　is　more　computationally　efficient　compared　with　the　Lorentz　finite-difference　time-domain　method.　An　accompanied　find　is　that　there　must　be　a　tradeoff　between　the　applicable　frequency　range　and　the　computation　cost　in　the　proposed　method.