1. A method for exchanging business card information by combining character recognition and image matching, and the method is applicable in a network system at least composed of a website server, a first client, and a second client; the website server has a business card database that prestores business card information; the first and the second clients have functions of capturing business card images, recognizing character information and extracting image features, characterized in that, the method for exchanging business card information comprises at least the following steps: 1) the first client captures a business card image of the second client user, and then recognizes character information on the business card image and extracts image features; 2) the first client uploads the recognized character information and the extracted image feature onto the website server, and sends a business card recognition request; 3) after the website server receives the business card recognition request, the website server retrieves all the prestored business cards that match the character information from the business card database according to the character information, respectively performs image feature matching on every business card image of the prestored business cards that have been retrieved with the business card image of the second client user, and generates a measurement value representative of the degree of similarity with respect to each candidate business card according to the similarities of the image features; 4) the website server sets one business card of greatest measurement value among all these prestored business cards, as the candidate business card; 5) whether or not the candidate business card belongs to the second client user is determined; and if so, the website server sends an exchanging request to the second client, and after the second client permits, the website server transmits the business card information of the second client user to the first client, while also transmitting the business card information of the first client to the second client; if not, the procedure ends.