The　multipath　decline　is　severe　in　limited　space　(such　as　in　tunnel,　in　laneway　and　in　building),　so　the　quality　of　mobile　communication　in　it　drops　sharply.　The　abilities　of　spread　spectrum　communication　technique　and　diversity　reception　technique　to　resist　multipath　decline　are　studied　firstly,　and　then　the　techniques　are　used　synthetically　in　mine　Code　Division　Multiple　Access　(CDMA)　mobile　communication　system.　Finally,　a　mine　CDMA　mobile　communication　system　forward　link-simulating　model　is　built,　a　bit　error　curve　of　the　model　is　got　and　the　simulating　result　demonstrates　that　the　performance　of　the　system　to　resist　multipath　decline　is　improved　awfully.　©　2010　IEEE.