A variable sampling plan is proposed for the reliability of an irreparable system, which can be expressed as average
reliable working time (ARWT). ARWT is a variable described by an exponential distribution. According to the
requirements of producer and customer for sampling inspection, the plans of producer and customer and a general plan
are given separately. The paper suggests taking the limit acceptable average reliable working time as the acceptance
standard. The plan of producer is designed by taking into consideration both the design index of average reliable time
and the risk of producer. The plan of customer takes into consideration both the refusing standard of reliable working
time and the risk of customer for designing. The general plan considers all risks of both producer and customer. There is
a great difference between plans in sampling numbers and protecting emphases.