The brittle-ductile transition (BDT) of particle toughened polymers was extensively studied in terms of morphology, strain rate, and temperature. The calculation results showed that both the critical interparticle distance (IDc) and the brittle-ductile transition temperature (TBD) of polymers were a function of strain rate. The IDc reduced nonlinearly with increasing strain rate, whereas TBD increased considerably with increasing strain rate. The effects of temperature and plasticizer concentration on BDT were discussed using a percolation model. The results were in agreement with the experiments.