The invention discloses a positive thermo-sensitive lithographic plate precursor. A resin layer and a thermo-sensitive layer are coated on a supporting body on a hydrophilic surface in order, wherein the resin layer contains a base soluble resin; the thermo-sensitive layer contains a base soluble resin, an infrared absorbent and a solvent resistant; and the precursor is characterized in that the base soluble resin contained in the resin layer contains an acrylic resin with a side chain structure of -L1-L2-R, wherein one of the L1 and L2 is -HN- while the other one of the L1 and L2 is -CH2-; and R is any one chosen from H, alkyl group, phenyl group and substituted phenyl group. The positive thermo-sensitive lithographic plate precursor provided by the invention, the resin layer of which contains the base soluble resin with excellent solvent resistance, has excellent solvent resistance and high developing tolerance.