The most common means of communication is language and the basic medium is speech. The interaction among humans and computer that is their communication is called human computer interface (HCI). Physical movement is one of the biggest challenges for the visually impaired. People with complete blindness or low vision often have a difficult time in self-navigating unfamiliar environments. Eventually people with blindness or low vision pose great difficulty in crossing lanes or move in huge crowed, So many people with blindness or low vision tend to bring a friend or family member for assistance .A personal digital assistant (PDA) was chosen because it combines small-size, computational resources and low cost price. Key technologies necessary are: Voice processing, Image processing, object recognition and speech synthesis. So that the problems faced by blind people can be reduced.