Microwave transmission line was designed for the module package of 4×25Gb/s electroabsorption modulated laser array. Simulations based on finite element method were carried out to determine the optimal structure. The optimized transmission line exhibits a transmission loss below 0.5dB and a reflection coefficient less than -13dB up to 30GHz. Meanwhile, the crosstalk between adjacent channels was effectively suppressed. The package of integrated light sources array was also studied, and an efficient package scheme was proposed.