The invention discloses a flexible mascara brush which comprises an adjusting device, a pull rod and a brush body, wherein the adjusting device consists of an adjusting end and a fixed end; the adjusting end of the adjusting device is fixedly connected with one end of the pull rod; the adjusting end of the adjusting device can drive the pull rod to make linear motion along the axial direction of the pull rod; the brush body is sheathed at the outer side of the pull rod; one end of the brush body is fixedly arranged at the fixed end of the adjusting device, and the other end thereof is provided with brush of kernel made of soft material; the other end of the pull rod is fixedly connected with the end of the brush of kernel far away from the brush body; and the pull rod is made of soft material which can be bended when being applied with force. The flexible mascara brush leads the brush of kernel to be bended and deformed under the force caused by pulling the pull rod, thus being convenient for use and simple in operation, easily adjusting the bending angle of the brush of kernel of the mascara brush and leading the shape of the mascara brush to be close to that of eyelash as much as possible; therefore, the flexible mascara brush can be more uniform and natural in brushing, and effectively prevents mascara cream from being brushed on the skin around the eyelash.