Applications based on sensitive property of porous silicon(PSi) were researched. As a kind of porous material, the feasibility of PSi as a getter material was studied. Five groups of samples with different parameters were prepared. The gas-sensing property of PSi was studied by the test system and suitable parameters of PSi were also discussed. Meanwhile a novel structure of humidity sensor, using porous silicon as humidity-sensitive material, based on MEMS process has been successfully designed. The humidity-sensing properties were studied by a test system. Because of the polysilicon layer deposited upon the PSi layer, the humidity sensor can realize a quick dehumidification by itself. To extend service life and reduce the effect of the environment, a passivation layer(Si_3N_4/was also deposited on the surface of electrodes. The result indicated the novel humidity sensor presented high sensitivity(1.1 p F/RH%), low hysteresis, low temperature coefficient(0.5%RH/?C/and high stability. Applications based on sensitive property of porous silicon (PSi) were researched. As a kind of porous material, the feasibility of PSi as a getter material was studied. Five gases of sensing materials of PSi was studied by the test system and suitable parameters of PSi were also discussed... a novel structure of humidity sensor, using porous silicon as humidity-sensitive material, based on MEMS process has been successfully designed. The humidity-sensing properties were studied by a test system. Because of the polysilicon layer deposited upon the PSi layer, the humidity sensor can realize a quick dehumidification by itself. To extend service life and reduce the effect of the environment, a passivation layer (Si_3N_4 / was also deposited on the surface of electrodes The result indicated the novel humidity sensor presented high sensitivity (1.1 p F / RH%), low hysteresis, low temperature coefficient (0.5% RH /? C / and high stability.