We have developed a portable multi-function digital hearing aid and its fitting system. The size of the hearing aid is 59 x 63 x 26 mm and the weight is 98 grams. The processing speed of its DSP chip is 6.6 MIPS. It works for 20 hours continuously on one Lithium-ion rechargeable battery. We introduced four kinds of basic software modules which can be combined: impulsive sound suppression, 3 channel compression, temporal consonant enhancement and enhancement of spectral contrast By combination of modules, 14 programs are installed in DSP on-chip ROM. The fitting system based on a personal computer measures the residual hearing ability of the hearing impaired and sends fitting parameters to customize the hearing aid. We will evaluate and improve the hearing aid this year.