A slide type mobile terminal and a method for processing signals thereof are disclosed in the present invention, wherein, a built-in auxiliary antenna is installed in an upper slide portion (10) of the slide type mobile terminal, meanwhile corresponding signal conversion modules (122, 312) are added to the upper slide portion (10) and a lower slide portion (30) respectively, which is used for converting an external high-frequency signal received by the built-in auxiliary antenna or an internal high-frequency signal generated by a main printed circuit board (PCB) from a single-ended signal to a differential signal, which are transmitted between the upper slide portion (10) and the lower slide portion (30) by a flexible printed circuit board (FPC) (20), so that the high-frequency signal is transmitted between the upper slide portion (10) and the lower slide portion (30) in form of differential signal.