The invention discloses a low-compression-ratio HIC-resistant and SSC-resistant pipeline steel plate and a preparation method thereof. The steel plate comprises chemical components: by weight, 0.03-0.05% of C, 0.15-0.30% of Si, less than or equal to 1.20% of Mn, less than or equal to 0.0020% of S, less than or equal to 0.010% of P, less than or equal to 0.30% of Cr, less than or equal to 0.20% of Ni, 0.035-0.055% of Nb, less than or equal to 0.030% of Ti, 0.015-0.040% of Alt, less than or equal to 0.0030% of O, less than or equal to 0.00015% of H, and the balance Fe and trace impurities. According to the low-compression-ratio HIC-resistant and SSC-resistant pipeline steel plate and the preparation method thereof, the ultralow-carbon, ultralow-sulfur and low-phosphorus component design is adopted, the effective total reduction rate of rolling of an austenite recrystallization zone is controlled to be more than or equal to 50%, the pass reduction rate of later three passes is controlled to be more than or equal to 18%, and the total reduction rate of an austenite non-recrystallization zone is controlled to be more than or equal to 70%. The steel plate obtained through the method has the advantages of excellent HIC-resistant and SSC-resistant performance, little alloy addition, low production cost, effective compression ratio being less than or equal to 10, good structure uniformity, fewer limitations to the thickness of casting blanks and the like, and is applicable to manufacturing of transporting pipelines for petroleum and natural gas containing acid media.