The　popularity　of　multi-core　systems　makes　software　parallelization　become　an　important　way　to　improve　performance.　As　a　mainstream　XML　query　language,　XQuery　is　the　core　of　XML　processing.　It　is　critical　to　take　full　advantage　of　multi-core　computing　to　improve　XML　processing　performance　through　parallelization　of　XQuery.　However,　usually　it　is　difficult　to　parallelize　XQuery　programs　because　of　the　nested　style　of　XQuery　expressions.　Moreover,　implicit　parallelism　is　necessary　to　simplify　the　development　of　parallel　XML　application.　In　this　paper,　we　propose　an　automatic　parallelization　approach,　which　can　automatically　select　proper　types　of　parallelism　for　a　specific　XQuery　query.　Specifically,　we　propose　a　functional　intermediate　language　called　pFXQL　(parallel　Functional　XML　Query　Language)　to　describe　parallel　query　plans.　pFXQL　has　parallel　semantics　and　is　well　complied　with　XQuery.　We　propose　a　cost　model　to　effectively　support　plan　generation　and　the　selection　of　a　preferred　plan.　The　model　estimates　both　computational　cost　and　parallel　cost.　We　implement　our　approach　in　XQuery　engine　and　conduct　experiments　on　various　multi-core　systems.　Experimental　results　verify　the　effectiveness　of　our　approach.