Abstract: This paper considers earliness/tardiness scheduling problem in which the jobs have fuzzy processing times on a single machine. The objective is to determine the optimal due-date, the optimal sequencing and the optimal processing times to minimize a total objective function based on earliness/tardiness, due-dates, completion times and the deviation of actual processing times from the maximum values of fuzzy interval numbers of processing times. The common due date assigement mathod is used to find the optimal common due date. Simulated annealing technique is presented for finding the optimal sequencing. In the end, we analysis performance measures of simulated annealing method in solving our problem using the computer simulated results.