diff --git a/paddle_quantum/utils.py b/paddle_quantum/utils.py
index d2f91c956b4aea3c236dd69f841ac8f9ce20ea85..d1d0ffe22432ca13f604e08ddc011b8fe3f6225f 100644
--- a/paddle_quantum/utils.py
+++ b/paddle_quantum/utils.py
@@ -924,9 +924,6 @@ class Hamiltonian:
         """
         coefs, pauli_words, sites = self.decompose_with_sites()
         n_qubit = 1
-        for site in sites:
-            if type(site[0]) is int:
-                n_qubit = max(n_qubit, max(site) + 1)
         for site in sites:
             if type(site[0]) is int:
                 n_qubit = max(n_qubit, max(site) + 1)