Smart Micro Grid (SMG), the system integrating distributed renewable generation, energy storage devices and intelligent inverter, provides efficient approach to utilize energy and decrease carbon emission. To achieve the reliable automated operation, intelligent control and transmission models should be employed in SMG system. Based on the theory of traffic engineering and distributed agent techniques, this paper proposes a novel Electric Information Flow Multi-QoS Constraints routing algorithm (EIF-MQC) applying to SMG advance measurement infrastructure. A Differentiated Services Code Point (DSCP) mapping model to abstract variety electric information from intelligent electronic devices into different QoS class traffic is designed. EIF-MQC computing optimal routing paths for each QoS class flow. In the paper, the mathematical proof to show the routing path computed by EIF-MQC is the shortest path is presented. Based on the infrastructure of Consortium for Electric Reliability Technology Solutions (CERTS) smart micro grid, the computer simulation to evaluate EIF-MQC is finished, compared with Open Shortest Path First (OSPF) and a routing protocol that is based on Load Balancing and a commonly used Shortest Path Routing protocol (LB-SPR). In both of the light communication load period and severe load ones, EIF-MQC has the excellent performance with balance bandwidth utilization rate, short transmission delay and low loss packets rate, all of which will be benefit to avoid transmitting congestion and improve the capability of Advance Measurement Infrastructure (AMI) system.