Accelerated life testing (ALT) of a product or material can obtain information quickly on its life or reliability information. Products or materials with operational period are often sampled and tested to evaluate their residual life. However, it is a main challenge how to deal with the operational period in statistical analysis for ALT application. The products are often treated as “new after operation” or “memoryless” and their operational period is ignored in residual-life evaluation on the assumption that their failure times follow exponential distribution. Since failure times of many mechatronic products follow Weibull distribution, the estimated precision of residual life of the products is low in the way mentioned above. This paper presents a novel approach based on equivalent time to statistically analyze ALT data of products or material with operational period. Estimated precision of the approach was studied by Monte Carlo simulation method. Results show that the approach can effectively estimate the residual life of the products and is more precise than that adopted previously.