A simple yet accurate interconnect parasitical capacitance model is presented. Based on this model a novel interconnect bus optimization methodology is proposed. Combining wire spacing with wire ordering, this methodology focuses on bus dynamic power optimization with consideration of bus performance requirements. The optimization methodology is verified under a 65 nm technology node and it shows that with 50% slack in the routing space, a 33.03% power saving can be provided by the proposed optimization methodology for an intermediate video bus compared to the 27.68% power saving provided by uniform spacing technology. The proposed methodology is especially suitable for computer-aided design of nanometer scale on-chip buses.