Thanks so much for your detailed reply. I’ve tried WeightedSampler, but it seems not work. The results comparison is as follows:


Before use WeightedSampler
Accuracy on training set: top1/5 = 53% / 82%
Accuracy on testing set: top1/5 = 48% / 77%


After use WeightedSampler
Accuracy on training set: top1/5 = 67% / 90%
Accuracy on testing set: top1/5 = 30% / 69%


I also tried WeightedLoss, the result is:
Accuracy on training set: top1/5 = 21% / 53%
Accuracy on testing set: top1/5 = 22% / 53%


So what else should I do now to further improve the performance of my model? Thanks again!