The work aims to develop a high temperature GPC method for accurate determination of the molecular weight information of medicinal low density polyethylene (polyethylene bottle). The sample was vibrated and dissolved at 150 ℃ for 2 h and the analysis was carried out on a highly crosslinked porous polystyrene/divinyl column which was eluted by a mobile phase of 250 mg/L antioxidant BHT in 1,2,4,-trichlorobenzene at a flow rate of 1 mL/min. The injection volume was 200 μL, the column temperature was 150 ℃, and the running time was 35 min. The influence of the dissolution temperature, dissolution time and antioxidants on the molecular weight determination was discussed, and the methods were optimized to compare with different determination methods for molecular weight. The methodology was examined for the optimized method and relative and absolute methods were used to calculate the molecular weight. The relative molecular weight of the three batches which were calculated by the relative method were 236 327, 238 832 and 240 631, respectively, and the polydispersity were 3.42, 3.48 and 3.66; the relative molecular weights calculated by the absolute method were 184 158, 186 674 and 184 006, respectively, and the polydispersity were 4.30, 4.25 and 4.24. The method can be used to determine the molecular weight information of the medicinal low density polyethylene accurately.