This　paper　proposes　a　new　method　to　realize　the　quantitative　trend　diagnosis　of　bearings　based　on　Protrugram　and　Lempel-Ziv.　Firstly,　the　fault　features　of　original　fault　signals　of　bearing　inner　and　outer　race　with　different　severity　are　extracted　using　Protrugram　algorithm,　and　the　optimal　analysis　frequency　band　is　selected　which　reflects　the　fault　characteristic.　Then,　the　Lempel-Ziv　complexity　of　the　frequency　band　is　calculated.　Finally,　the　relationship　between　Lempel-Ziv　complexity　and　fault　size　is　obtained.　Analysis　results　show　that　the　severity　of　fault　is　proportional　to　the　Lempel-Ziv　complexity　index　value　under　different　fault　types.　The　Lempel-Ziv　complexity　showed　different　trend　rules,　respectively,　in　the　inner　and　outer　race,　which　realized　the　quantitative　trend　diagnosis　of　bearing　faults.