We　study　a　planar　piecewise　linear　differential　system　with　three　zones　and　asymmetry　[Formula　presented],　where　xg(x)＞0　for　x≠0　and　the　graph　of　F(x)　is　a　U-shaped　curve.　The　system　was　researched　in　Llibre　et　al.　(2015)　for　its　limit　cycles.　However,　the　number　and　hyperbolicity　of　limit　cycles　were　still　unclear　in　some　parameter　regions.　We　give　the　exact　number　of　limit　cycles　and　obtain　the　hyperbolicity　of　limit　cycles　in　these　parameter　regions,　where　the　maximum　number　is　two.　©　2018　Elsevier　B.V.