1. A method for searching target clients, applied to a mobile device coupled to a network, comprising: inputting at least one keyword; generating a target position by a positioning unit of the mobile device; generating a target time by a time generating unit of the mobile device; generating a target clients search message according to the at least one keyword, the target position and the target time, and transmitting the target clients search message to a server coupled to the network through the network; receiving a search result transmitted by the server through the network, wherein the search result comprises at least one of a target clients amount, a target clients density and a target clients occurrence probability, which are retrieved from at least one social networks data and corresponding to the at least one keyword, the target location and the target time; and displaying a map combined with the search result.