A new microstrip low pass filter (LPF) with defected ground structure (DGS) is proposed in this article. The DGSs consists of reshaped rectangular dumbbell slot and four groups of Z-shape slots. The microstrip line with DGS gave good rejection band extend from 3.0 to 9 GHz with acceptable pass band. The microstrip line with open circuit stubs (without DGS) gave good rejection band at the high frequency from 9 to 14 GHz. Using both structures results in LPF with wideband rejection from 3.37 to 14 GHz with attenuation less than (26.0dB) and good passband less than (25 dB). An equivalent circuit for the proposed LPF was given. The realized filter size was 34.0  34.0 mm2, and it gave good agreement with simulated results