The　paper　researches　on　the　offset　error　of　self-triggering　pulsed　mini　laser　radar.　It　theoretically　analyzes　the　variation　of　space　charge　region　of　PN　junction　in　receiving　photodiode.　The　variation　value　is　affected　by　the　different　incident　light　power.　One　of　conclusion　is　the　laser　pulse　time-of-flight　affected　by　the　variation　of　incident　light　power.　Another　conclusion　is　the　laser　pulse　width　affected　by　the　variation　of　incident　light　power　as　well.　The　paper　proposes　the　basic　equations　to　describe　this　phenomenon.　In　addition,　the　new　designed　experimental　devices　are　used　to　prove　that　the　theoretical　analysis　is　true.　This　new　system　can　effectively　solve　the　offset　error　problems,　and　the　negatively　impact　of　offset　error　will　be　eliminated　on　the　receiver　of　self-triggering　pulsed　mini　laser　radar　system.　©　(2014)　Trans　Tech　Publications,　Switzerland.