Abstract: In order to solve the problem of optimizing of composite right/left handed (CRLH) structure leaky-wave antennas, a new method of optimal design of coplanar waveguide CRLH (CPW-CRLH) structure leaky-wave antennas was proposed. A synthesis method as well as computer aided design (CAD) software based on MATLAB is proposed to minimize the number of trials and accelerate the designing procedure, by successfully dealing with parasitic effects resulting from the size of elements. Then a miniaturized wide band leaky-wave antenna was designed by this method together with accelerated genetic algorithm (AGA). Both the simulation and measurement of the fabricated antenna validate the feasibility and exactness of the optimization and synthesis method. This research provides some technical guidance for the wide application of CRLH-TL structures.