High performance liquid chromatography（HPLC）was the most simple and sensitive detection method of polymer concentration，however，HPLC can only test the total polymer concentration. In a practical application，the preformed particle gel （PPG）and partially hydrolyzed polyacrylamide（HPAM）are often used together in order to improve oil-displacement efficiency. To achieve the detection of PPG in produced liquid of oilfield（containing HPAM）using HPLC method，a new sample preparation method was put forward based on the structural differences between HPAM and PPG，the crosslinking agent and gel breaker was added into the sample， respectively，HPAM would be precipitated off，while PPG would still in the sample，resulting in that HPAM would not interfere with the detection of PPG using HPLC method. The experiment results showed that at first，Al（NO₃）₃ was added into the sample at the mass ratio of the Al（NO₃）₃ to the total polymer of 10∶1；after about 3 min，H₂O₂ was added into the sample at the mass ratio of H₂O₂ to the total polymer of 150∶1，as a result，the complete precipitation of HPAM achieved and the PPG could be detected alone using HPLC method. This method had good precision and standard addition recovery rate，the broad linear range was 10—200 mg/L，and the lowest limit of detection was 5 mg/L.