A lawn mower comprising: a blade assembly (200, 910a, 920a, 930) configured to perform a cutting function; a deck formed with an accommodating space for accommodating at least part of the blade assembly; and a power mechanism configured to drive the blade assembly to rotate about a rotation axis; wherein the blade assembly comprises a cutting blade (300, 910, 920b, 931) configured to be driven by the power mechanism to rotate about the rotation axis, the cutting blade having a cutting edge, and a chopping device (400, 910b, 920, 932) comprising a chopping body (410, 921),and a plurality of branching ports (430, 923); wherein the chopping body is configured to be driven by the power mechanism to rotate, and the chopping body is a plate which comprises a mounting portion (412, 921a) and an extension wing (413, 921b), wherein the mounting portion is connected with the power mechanism and the extension wing extends radially outward from the mounting portion; characterized in that the lawn mower is configured for chopping grass and leaves into small pieces; the chopping device comprises a plurality of chopping teeth (420, 922), each extending upward or downward from the chopping body, and one of the plurality of branching ports is provided between two adjacent ones of the plurality of chopping teeth; the plurality of chopping teeth is provided on the extension wing; the extension wing has a leading edge (414, 921e) and a trailing edge (415, 921d), the leading edge is located in front of the trailing edge when the extension wing rotates, and the plurality of chopping teeth are provided on at least one of the leading edge or the trailing edge; and the chopping device installed axially above the cutting blade. a blade assembly (200, 910a, 920a, 930) configured to perform a cutting function; a deck formed with an accommodating space for accommodating at least part of the blade assembly; and a power mechanism configured to drive the blade assembly to rotate about a rotation axis; wherein the blade assembly comprises a cutting blade (300, 910, 920b, 931) configured to be driven by the power mechanism to rotate about the rotation axis, the cutting blade having a cutting edge, and a chopping device (400, 910b, 920, 932) comprising a chopping body (410, 921),and a plurality of branching ports (430, 923); wherein the chopping body is configured to be driven by the power mechanism to rotate, and the chopping body is a plate which comprises a mounting portion (412, 921a) and an extension wing (413, 921b), wherein the mounting portion is connected with the power mechanism and the extension wing extends radially outward from the mounting portion; characterized in that the lawn mower is configured for chopping grass and leaves into small pieces; the chopping device comprises a plurality of chopping teeth (420, 922), each extending upward or downward from the chopping body, and one of the plurality of branching ports is provided between two adjacent ones of the plurality of chopping teeth; the plurality of chopping teeth is provided on the extension wing; the extension wing has a leading edge (414, 921e) and a trailing edge (415, 921d), the leading edge is located in front of the trailing edge when the extension wing rotates, and the plurality of chopping teeth are provided on at least one of the leading edge or the trailing edge; and the chopping device installed axially above the cutting blade.