The invention provides a PVC film and a preparation method thereof. The preparation method comprises the following steps: mixing PVC, a plasticizer and a stabilizer to obtain a mixture; sequentially performing banburying on the mixture, plasticizing and calendaring molding to obtain the PVC film. The PVC film comprises 100 parts by weight of PVC, 18-36 parts by weight of the plasticizer and 1-6 parts by weight of the stabilizer; the plasticizer comprises TOTM, the TOTM occupies 30-100 percent of the total weight of the plasticizer; in the mixing step, first stirring and second stirring are carried out; the second stirring speed is higher than the first stirring speed; the second stirring time is 300-400 s. By adopting the TOTM plasticizer and controlling the content of the TOTM plasticizer within the above range, the second stirring time is controlled within the above range, so that all the components can be uniformly mixed; as the TOTM plasticizer is excellent in heat resistance, the PVC film has high temperature resistance, the risk of hot deformation at a high temperature is reduced.