In this study, a self-designed powder needleless injection system was compared with subcutaneous injection using a needle and syringe to deliver tetanus toxoid (TT) into mice to elicit immunity.  First of     all, factors influencing the prepartion of TT into powder by being absorbed on aluminium hydroxide were     investigated and the micromeritic characters of Al(OH)₃-TT powder were observed with optical microscope and laser particle analyzer.  The results showed that salt concentration and absorption time had an enhancive effect on drug loading, but the pH value and temperature did not influence the absorption reaction obviously.  The  absorption reaction was optimized with sodium chloride concentration of 0.4 mol·L⁻¹ and lasting for 10 min.  The average diameter of Al(OH)₃-TT powder prepared with conditions optimized above was (60.6 ± 4.4) μm.  The immunization effect of TT was determined through enzyme-linked immunosorbent assay (ELISA) of the concentration of IgG antibody elicited by TT.  With delivery of Al(OH)₃-TT (of 30 μg TT) by powder needleless injection to mice, the IgG antibody concentration were (6.19 ± 0.52) and (10.70 ± 0.78) U·L⁻¹ after immunization of 4 and 8 weeks, respectively, while the values were (4.25 ± 0.58) and (7.48 ± 0.57) U·L⁻¹ by subcutaneous  injection (of 20 μg TT) using a needle and syringe.  The results suggested that the self-designed powder    needleless injection of Al(OH)₃-TT was comparable to subcutaneous injection with a good immunity.