Why DataGridComboBoxColumn's ItemsSource will refresh after DataGrid reload ?

A very quick and easy way is to subclass ObservableCollection and suspend notifications when AddRange is called. You could try to refer to it according to your needs.

 public class MyObservableCollection<T> : ObservableCollection<T>  
	{  
		private bool myNotification = false;  
  
		protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)  
		{  
			if (!myNotification)  
				base.OnCollectionChanged(e);  
		}  
  
		public void AddRange(IEnumerable<T> list)  
		{  
			if (list == null)  
				throw new ArgumentNullException("list");  
  
			myNotification = true;  
  
			foreach (T item in list)  
			{  
				Add(item);  
			}  
			myNotification = false;  
			OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));  
		}  
	}  

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