Robust-index method is proposed to tackle the challenges of uncertainties caused by customer behavior in order to minimize comfort violation in household load scheduling. Robust indexes for different kinds of loads are developed and integrated into the load scheduling optimization problems in the form of additional constraints, and thus the obtained load schedules are able to reach the expected robust level. The robust-index method is simple in modeling, independent of historical data, and with low additional computational burden. Simulation results verified the validity of the proposed method and demonstrated their application in load scheduling.