As the development of Micro Electromechanical Systems (MEMS),decreasing the components size becoming more and more important.Especially for RF-MEMS,the RF components are normally larger than other parts because of the relation between the components and electro magnetic wavelength.To resolve this problem,a compact micro CRLH (composite right/lefi-handed) band reject filter based on MEMS technology and left handed material theory was designed and fabricated.The length of the main part is only 1/20 of the working wa,elength.It can be integrated into RF-MEMS where micro RF components are necessary.