The polymer was prepared by radical polymerization with iso-octyl acrylate and 1-octene as raw materials. Effects of initiators and its dosage, reaction temperature, reaction time and the mole ratio of raw materials on the yield and performance of the product were investigated. The results showed that 1-octene can participate well in copolymerization reaction when dosage of di-t-butyl peroxide (DTBP) was more than 3% and the temperature was higher than 110 ℃. The reaction could be completed in 12 h. A better result could be obtained when the reaction temperature was 130 ℃ and dosage of initiator (DTBP) was 6%. The average molecular weight was from 7800 to 61 100 and molecular weight distribution was about 2.3 using gel permeation chromatography for determination. The product can be used as viscosity index improver since its viscosity index range is from 200 to 380. Meanwhile, the flash point and pour point of the copolymers suggest that it can be used as good lubricant base oil.