There are a large number of capacitor units within a capacitor bank. The working environment is obvious different among these units. The capacitance values can be influenced by temperature, thus affecting the unbalance current protection’s reliability and sensitivity. The influence of temperature is discussed, which is based on double-bridge unbalance current protection. The theoretical analysis is carried out, and the calculation formula of the unbalance current due to temperature variation is obtained. The work in this paper also contains the simplification of the theory and practical protection setting scheme. The results are demonstrated by simulation with PSCAD. This method has important value both on theory and practical application. This work is supported by National Natural Science Foundation of China (No. 51277009).