Floating　catalyst　chemical　vapor　deposition　(FCCVD)　can　produce　buckypaper,　a　kind　of　CNT　film,　at　large-scale　with　low　cost.　However,　individual　CNTs　in　the　buckypaper　are　mostly　randomly　oriented,　which　significantly　limits　their　electrical　and　mechanical　properties.　Here　we　report　an　innovative　approach,　water-assisted　shear　stretching　(WASS),　which　can　significantly　improve　CNT　alignments　and　consequently　enhance　the　electrical　and　mechanical　properties.　In　addition,　we　define　a　unique　＂alignment　factor＂　to　quantify　the　alignment　degree,　and　to　estimate　the　effect　of　alignment　on　the　mechanical　and　electrical　properties　of　CNT　assemblies.　The　high　mechanical　strength　and　excellent　electrical　conductivity　of　the　WASS-processed　buckypaper　enhance　their　potential　for　applications　in　new　electronic　technologies　and　high-strength　lightweight　aerospace　structures.