The invention discloses Cr-Mo-Si-V-series cold work die steel and a preparation method thereof. The Cr-Mo-Si-V-series cold work die steel comprises the following components of, by weight, 0.85-1.65% of C, 0.80-1.10% of Si, 0.30-0.60% of Mn, less than 0.0050% of P, less than 0.0050% of S, 1.60-3.20% of Mo, 7.00-14.00% of Cr, 0.15%-0.55% of V and the balance Fe and other inevitable impurities. The preparation method comprises the following steps that raw materials undergo smelting, casting and forging to form a forged blank, moreover, cooling is performed, the corresponding heating rate is controlled, two times of heating treatment is performed, primary pretreatment is completed, then the corresponding heating rate and the corresponding cooling rate are controlled, one time of heating treatment and two times of cooling treatment are performed again, then secondary pretreatment is completed, and then quenching and tempering are performed to prepare the cold work die steel. The preparationmethod has the advantages that the production cost is low, pollution is avoided, the operation is easy, through the two times of pretreatment processes, the carbide spheroidization effect is remarkably improved, and the hardness is reduced, so that next-step heat treatment requirements are met.