How to keep the accuacy when convert a pytorch model to TensorRT in FP16 mode

I want to use TensorRT FP16 mode to accelerate my pytorch model, but there is a loss of precision. My question is how can I use the mixed precision training of pytorch, to avoid the loss of accuracy when converting to a TensorRT FP16 model. I have tried the torch.cuda.amp.autocast to training the model, but it still lost some precision.