diff --git a/model_training_nnn_tpu/trainer_tf.py b/model_training_nnn_tpu/trainer_tf.py
index d4598c6..1917585 100644
--- a/model_training_nnn_tpu/trainer_tf.py
+++ b/model_training_nnn_tpu/trainer_tf.py
@@ -511,18 +511,11 @@ class BrainToTextDecoderTrainerTF:
                 loss = self.ctc_loss(loss_input, clean_logits)
                 loss = tf.reduce_mean(loss)
 
-            # Scale loss for mixed precision
-            if self.mixed_precision:
-                scaled_loss = self.optimizer.get_scaled_loss(loss)
-            else:
-                scaled_loss = loss
+            # TensorFlow混合精度处理：不需要手动scaling，Keras policy自动处理
+            # TPU v5e-8使用bfloat16，不需要loss scaling
 
-        # Calculate gradients
-        if self.mixed_precision:
-            scaled_gradients = tape.gradient(scaled_loss, self.model.trainable_variables)
-            gradients = self.optimizer.get_unscaled_gradients(scaled_gradients)
-        else:
-            gradients = tape.gradient(scaled_loss, self.model.trainable_variables)
+        # Calculate gradients - TensorFlow自动处理混合精度
+        gradients = tape.gradient(loss, self.model.trainable_variables)
 
         # Clip gradients
         if self.args['grad_norm_clip_value'] > 0: