The smart city is set to be the next important stage in human history. It consists of numerous Cyber-physical systems (CPS) that can be endowed with different levels of intelligence. However, the increasing use of the CPS and their application to key infrastructure components means that failures can result in disruption, damage and even loss of life. Avoiding these consequences is not a trivial problem and some researchers propose that cloud computing can provide the effective and sustainable services for smart city. With the integration of CPS and cloud computing, sensor-cloud system becomes popular in many fields where the physical nodes can be shared with multiple users, which can achieve high performance computing. However, when a physical sensor node receives multiple services commands simultaneously, there will be some service collisions, namely, coupling resource management problem. This coupling resource management problem leads to the failures of services. In order to solve the coupling resource management problem, we propose a fog computing model and extend the Hungarian algorithm to manage the coupling resource which can get smaller delay to realize effective and sustainable services. The fog computing layer acts as a buffer and controller between CPS layer and cloud layer which can handle malicious attacks to build highly sustainable systems. Experimental results and theoretical analysis show that our method can reduce the coupling computing and increase the resource utilization to make systems more effectively.