In order to investigate the influence of pre-treatment methods such as water wash， acid wash and molten salt on biomass pyrolysis characteristic，rubber seed shell was selected as biomass feedstock.Deionized water，hydrochloric acid，sulfuric acid and methanoic acid and mixed acid as well as KCl and NaOH，whose mass fractions were 5 %，10 % and 15 %，respectively，were used to wash rubber seed shell，and the thermal decomposition behaviors and comprehensive index of rubber seed shell pyrolysis were analyzed. At the sametime，the kinetic parameters were studied. The results showed that water wash and acid wash can make thermo-gravimetric analysis and derivative thermogravimetric analysis curves of rubber seed shell pyrolysis shift to higher temperature section，and the maximum weight loss rate and temperature increased，but the melted salt was decreasing. The impacts of the concentration of hydrochloric acid and methanoic acid were negligible，but that of sulfuric acid was significant which became obvious with the increasing concentration. Acid wash was in favor of the emission of volatile matters contained in rubber seed shell，and can eliminate the sylvite.The ability order of three acids was as follows：sulfuric acid，hydrochloric acid and methanoic acid. The thermal comprehensive characteristic index of pyrolysis decreased after rubber seed shell was pretreated，and changed with the acid concentration.