A　three-dimensional　W-M　fractal　sliding　model　of　double　rough　surfaces　was　established,　and　the　factors　of　interface　shear　strength　influenced　the　whole　sliding　process　was　considered.　The　velocity　in　Z　direction　of　sliding　processes　was　analyzed　using　the　finite　element　analysis　and　taking　into　account　of　adhesion　factors　in　the　process　of　contact.　The　numerical　results　showed　that　the　velocity　in　Z　direction＇s　fluctuation　is　larger,　and　the　higher-frequency　component　is　more　with　the　decrease　of　the　interface　shear　strength.　Compared　with　experimental　results　and　related　documents,　it　is　concluded　the　rationality　of　the　results.　The　contact　model　between　two　rough　solids　will　lay　a　foundation　to　further　research　on　the　substance　of　the　process　of　friction　and　wear.　©　(2014)　Trans　Tech　Publications,　Switzerland.