The present invention relates to a synchronous dual channel QPSK demodulation device and a method for demodulating the same in a CDMA system. The present invention relates to a synchronous dual channel QPSK modulator in a CDMA system that receives two input signals through two input stages and modulates them. A first Walsh cover means for receiving a first input signal through a first input terminal and performing Walsh covering and outputting the second Walsh covering means for receiving a second input signal through a second input terminal and outputting the Walsh covering; Addition means for adding and outputting the output signal of the first Walsh cover means and the biased DC signal, first pseudo modulation means for pseudo-modulating and outputting the output signal of the addition means with a predetermined pseudo noise, and the second Walsh Second modulator means for modulating and outputting the output signal of the cover means with the pseudo noise; and an output signal of the first modulator means. First pulse shaping means for shaping a wave and outputting a pulse signal, second pulse shaping means for shaping an output signal of the second quadrature modulation means into a pulse wave, and outputting a pulse signal, and an output signal of the first pulse shaping means First amplitude modulating means for amplitude modulating and outputting a modulated signal to a predetermined modulation signal, second amplitude modulating means for amplitude modulating and outputting an output signal of the second pulse shaping means to a predetermined modulation signal, and the first amplitude modulating means. And a second adding means for adding the output signal of the signal and the output signal of the second amplitude modulation means to output to the antenna. Therefore, the effect is to eliminate the crosstalk interference, which has been one of the factors degrading the system performance. The quality is up.