The invention discloses a coal slurry flotation collector and a preparation method thereof, and belongs to the technical field of coal flotation. The coal slurry flotation collector is transparent liquid composed of hydrocarbon-type oil, sec-octyl alcohol and a surface active agent having a promotion effect on floatation. The preparation method includes the steps that firstly, Span80 and Tween80 mixed surface active agent is prepared; then, a mixture of the hydrocarbon-type oil and water is prepared, and the mixed surface active agent is added in the mixture; the mixture is stirred, and the sec-octyl alcohol is dropwise added at the same time; and when the solution becomes clear from the muddy state, the drop-by-drop addition of the sec-octyl alcohol is stopped, and the coal slurry flotation collector is prepared. The aims of reducing the oil consumption and increasing the clean coal recovery rate can be achieved by using the collector for coal slurry floatation. The coal slurry flotation collector has the beneficial effects of being convenient to use, low in reagent consumption, good in floatation effect, and the like. During floatation, microemulsion can be sufficiently dispersed in ore pulp, floatability of concentrate can be enhanced, attachment of fine silt to the surface of the concentrate can be relieved, and quality of the concentrate can be improved.