diff --git a/deepmd/utils/data.py b/deepmd/utils/data.py
index ae4a484909..26a27c82d7 100644
--- a/deepmd/utils/data.py
+++ b/deepmd/utils/data.py
@@ -14,6 +14,7 @@
 from typing import (
     Any,
     Optional,
+    Union,
 )
 
 import numpy as np
@@ -135,8 +136,7 @@ def __init__(
         self.shuffle_test = shuffle_test
         # set modifier
         self.modifier = modifier
-        # calculate prefix sum for get_item method
-        frames_list = [self._get_nframes(item) for item in self.dirs]
+        frames_list = [self._get_nframes(set_name) for set_name in self.dirs]
         self.nframes = np.sum(frames_list)
         # The prefix sum stores the range of indices contained in each directory, which is needed by get_item method
         self.prefix_sum = np.cumsum(frames_list).tolist()
@@ -338,8 +338,10 @@ def get_numb_set(self) -> int:
 
     def get_numb_batch(self, batch_size: int, set_idx: int) -> int:
         """Get the number of batches in a set."""
-        data = self._load_set(self.dirs[set_idx])
-        ret = data["coord"].shape[0] // batch_size
+        set_name = self.dirs[set_idx]
+        # Directly obtain the number of frames to avoid loading the entire dataset
+        nframes = self._get_nframes(set_name)
+        ret = nframes // batch_size
         if ret == 0:
             ret = 1
         return ret
@@ -578,18 +580,27 @@ def _shuffle_data(self, data: dict[str, Any]) -> dict[str, Any]:
                 ret[kk] = data[kk]
         return ret, idx
 
-    def _get_nframes(self, set_name: DPPath) -> int:
-        # get nframes
+    def _get_nframes(self, set_name: Union[DPPath, str]) -> int:
         if not isinstance(set_name, DPPath):
             set_name = DPPath(set_name)
         path = set_name / "coord.npy"
-        if self.data_dict["coord"]["high_prec"]:
-            coord = path.load_numpy().astype(GLOBAL_ENER_FLOAT_PRECISION)
+        if isinstance(set_name, DPH5Path):
+            nframes = path.root[path._name].shape[0]
         else:
-            coord = path.load_numpy().astype(GLOBAL_NP_FLOAT_PRECISION)
-        if coord.ndim == 1:
-            coord = coord.reshape([1, -1])
-        nframes = coord.shape[0]
+            # Read only the header to get shape
+            with open(str(path), "rb") as f:
+                version = np.lib.format.read_magic(f)
+                if version[0] == 1:
+                    shape, _fortran_order, _dtype = np.lib.format.read_array_header_1_0(
+                        f
+                    )
+                elif version[0] in [2, 3]:
+                    shape, _fortran_order, _dtype = np.lib.format.read_array_header_2_0(
+                        f
+                    )
+                else:
+                    raise ValueError(f"Unsupported .npy file version: {version}")
+            nframes = shape[0] if len(shape) > 1 else 1
         return nframes
 
     def reformat_data_torch(self, data: dict[str, Any]) -> dict[str, Any]: