According　to　the　statistics　and　phenomenon　analysis　of　water　bursts　occurred　in　Maluqing　Tunnel　of　Yiwan　Railway,　the　characteristic　and　the　mechanism　of　water　burst　disaster　occurring　in　water-enriched　karst　tunnel　with　high　hydraulic　pressure　is　summarized.　Before　the　water　burst　occurs,　dissolve　gap　and　vascular　are　expanded　to　confluence　by　water　pressure　and　the　surrounding　underground　water　is　taken　over.　When　water　storage　and　cavity　static　pressure　reach　the　critical　values,　the　blockage　layer　at　the　bottom　of　the　cavern　will　be　broken　through　and　water　burst　will　occur　instantaneously.　By　analyzing　the　observation　results　of　rainfall,　water　inflow,　water　seepage　test　and　water　level,　the　water　inflow　is　predicted　by　the　rainfall　infiltration　method　and　statistics　analysis　method　respectively　and　the　key　parameters　of　risk　control,　such　as　water　storage　volume　of　cavern,　accumulation　rate　and　mechanical　properties　of　sedimentation　and　thickness　of　the　confined　bedrock　are　also　presented.　In　addition,　some　quantitative　indicators　of　secure　access　to　the　tunnel　are　obtained.