A kind of serial combined rod of phononic crystals (SCRpc) is proposed which introduces the thought of phononic crystals into the design of combined rods in series. Transfer matrix method is used in theoretical analysis, numerical solutions and optimal calculation of vibration transmissibility are obtained and further simulations are preceded in finite element software. The results show that: firstly, a SCRpc which can realize the wave type transformation may make good use of bending, longitudinal and torsional band gaps duo to the effect of coupled in-plant and out-of-plant vibration at the junction of rods , so as to achieve three-dimensional and broadband vibration suppression. The structure is a good type of multi-dimensional and broadband vibration isolating element. Secondly, the intersect angles of SCRpc have significant impacts on the performance of the vibration reduction. According to the need of stop band, the optimal design of the intersect angles of SCRpc can be conducted by genetic algorithm. Thirdly, different loading angles have the similar influencing law when being acted on various combinations of intersection angles, i.e. the attenuation performance of the 0 or 90 degrees case is much better than that of others.