The process of transmit-receive and transmission delay for GSM short message are introduced. A analysis is put forward after switching on GSM network short message transmit-receive stop and connecting with computer serial port. The method procedure to solving GSM modem short message transmit-receive stop with modular function allocating incremental port number is presented. Analysis shows that increase port number can advance the short message transmit-receive velocity and select fit port number according to efficiency charge ratio. In view of application example of short message transmit-receive flow diagram, it shows that the method is good efficiency charge ratio，and it can meet the requirements of fix or low speed vehicle mobile terminal transmission and GPS positioning data and other short message documentary.