In this investigation, maleic anhydride(MA) and glycerol(GA) as the processing additive to improve the precessing ability of biodegradable low-density polyethylene/tapioca starch (LDPE/TS) blends were studied. The influence of plasma treatment of LDPE (PLDPE) and the influence of MA adding method on the properties of LDPE/TS blends were also investigated. The melt flow index of LDPE/TS/GA (150g/500g/150g) was increased from 1.2g/10min to 20.2g/10min by adding 3g of MA. Furthermore, as the LDPE was treated by plasma, the melt flow index of PLDPE/TS/GA (150g/500g/150g) was increased from 0.3g/10min to 15.3g/10min by adding 1g MA. On the other hand, the mechanical strength damping of the blends could be markedly decreased. The thermal resistance of GA also could be markedly increased from about 150degreesC to about 250degreesC as the MA was dissolved into GA before DSC measurement. FTIR spectra show that the MA reacted with GA as the MA was dissolved into GA. This result cause that the compability between LDPE and ST was improved. It could be evidenced by SEM micrographics. The MA was dissolved into GA before compounding favor for biodegradation. In this investigation, the highest weight loss percentage of all blends was about 95%.