In this paper, a CPW lowpass filter with the spurious-reduced characteristic is designed by using DGS(Defected Ground Structures). By cascading two lowpass filters with different harmonic characteristics the spurious is reduced below - 15 dB. Additionally by combining a dumbbell shaped DGS to the filter we achieved a satisfactory spurious level of less than -25 dB to above three times cutoff frequency without any repeated passband. The fabricated LPF shows a compact size of $17.2mm{ imes}6.8mm$, a cutoff frequency of 6 GHz, and a sharp skirt response of 7-order with two notch frequencies. The measured frequency responses agree well with simulated ones.