Copolymer AM/C5 was synthesized by copolymerization of hydrophobic monomer(C5 petroleum resin) with acrylamide, and then the novel hydrophobic polymer Mannich base was prepared from aminomethylation with copolymer. Effect of mass ratio of C5 petroleum resin and acrylamide, initiator dosage, reaction temperature and pH value on polymerization were investigated. Effect of reaction time, temperature and pH value on apparent viscosity of mannich base were discussed. The structure of products was characterized by FTIR and 1HNMR, and the performance analyzed. The results showed that the optimum conditions of copolymerization were as follows：reaction temperature 40℃, pH 8, initiator mass fraction 0.5% of the monomer mass, m(AM):m(C5)=15:1. The Mannich base solution has a higher value of apparent viscosity is 418 mPa·s under the conditions of reaction time 5 h, temperature 60~70℃, pH 9, n(AM):n(HCHO):n(NH(CH3)2)=1:1.1:1.5. When the temperature was 90℃, the viscosity reserved rate was more than 43.3%; when the mass concentration of NaCl、CaCl2 was 2000 mg/L, the viscosity retention rate was 32.8% and 21.7%,respectively. Therefore, the Mannich base possessed the excellent tackability; temperature tolerance and salt resistance.