In order to filtrate the microwave signals in micro electronic mechanical systems,a micro Composite Right/Left Handed(CRLH) transmission line band reject filter is presented,and the design theory,structure characteristics and fabrication process of the filter are also studied. According to the Left Handed Material (LHM) theory,the filter structure with a meander gap is introduced,and the equivalent circuit of the meander gap structure is obtained by comparing to the conventional interdigital capacitor structure. Then,the advantage of the meander gap structure is discussed by taking a cell of the meander gap as an example,and the results show that the equivalent circuit parameters in the meander gap structure are larger than that of the conventional interdigital capacitor structure. Finally,the fabrication process is introduced by combining different MEMS (Micro Electromechanical Systems) technologies,such as sputtering,lithography,electroplating and etching. By the MEMS technology,a band reject filter with the size of the main part of 5 mm×7 mm is developed. The simulated and experimental results show that the phase shift constant of the band reject filter is negative at the high frequency (2.1-5.2 GHz,left handed region),and the phase velocity flows just to the opposite direction of the energy flow in the left region. Moreover,the relative pass bandwidth in a left handed region is 82.7%. Compared with other designs,this filter shows his advantages in small sizes and large working bands at the left handed region.