The invention provides machinable concrete and a preparation method thereof. The machinable concrete is prepared from, by mass, 32-42 wt% of resin aggregate, 34-44 wt% of sand, 12-22 wt% of cement, 6.5-8.5 wt% of water, 2.1-3.2 wt% of limestone powder and 0.12-0.22 wt% of admixture. According to the machinable concrete, by replacing traditional sandstone aggregate with the resin aggregate, the lightweight of the concrete is achieved, the transportation pressure of the concrete is reduced, and meanwhile as a novel lightweight concrete material, the concrete is convenient to cut and machine andsuitable for the construction of complicated working conditions.