With rapid growing of wireless and mobile technologies, mobile devices are part and parcel of our lives. Nowadays GPS (Global Positioning Service) technology is combined with mobile devices. People use some Internet applications, e.g. mobile fund transfer, e-commerce, game online and theatre booking. These applications should support digital signature service for more security. Because mobile device is low-computation capability and limited battery life, it is not suitable to use digital signature protocols, which are based on asymmetric cryptographic algorithm, with mobile devices. And it does not use advantage of GPS technology. We present "location based digital signature on mobile devices" with geo-encryption to generate digital signature. This method reduces the burden on mobile devices, the computation time of the requester by almost 98%, compared with Abe-Fujisaki's RSA-based partially blind signature and decreases communication between sender and receiver