Air conditioners (ACs) are widely considered as good candidates to provide operating reserve. Demand response rebound, i.e., the rebound peak of aggregate power, may exist when ACs are controlled by changing the set point temperature. The rebound peak during the recovery period, named as the lag rebound, may cause significantly higher demand than that prior to the reserve deployment event. The rebound peak during the reserve deployment period, named as the lead rebound, is rarely considered in previous researches but will constrain the duration time to a short period (e.g., 10 min), which greatly limits the utilization of ACs. This chapter proposes an optimal sequential dispatch strategy of ACs to mitigate the lead-lag rebound and thus realize flexible control of the duration time from minutes to several hours. To quantify the effects of lead-lag rebound, a capacity-time evaluation framework of the operating reserve is developed. On this basis, ACs are grouped to be dispatched in sequence to mitigate the lead-lag rebound. The co-optimization of sequential dispatch on the capacity dimension and time dimension forms a mixed integer nonlinear bi-level programming problem, in which the consumers’ thermal comfort is also guaranteed. Case studies are conducted to validate the proposed strategy.