The invention provides a heat-conducting fin with oriented graphene fibers and a preparation method thereof. The preparation method comprises the following steps: 1, uniformly mixing matrix resin, graphene fibers and heat-conducting powder through a stirring device so as to obtain a mixture; 2, pouring the mixture into an annular groove of a forming device, starting the forming device to enable the annular groove to rotate around the center of the forming device, orienting graphene fibers in the mixture along a flowing direction, and heating the mixture to obtain an annular solid; 3, placing the annular solid in an oven for heating and curing; and 4, slicing the heated and cured annular solid in the radius direction of a circular ring by adopting a slicing device so as to obtain the heat-conducting fin with the graphene fibers arranged in the thickness direction in an oriented manner. The preparation method of the invention prepares the heat-conducting fin with the graphene fibers oriented in the thickness direction, and the prepared heat-conducting fin has better heat-conducting property.