Hi Nazmi,
Thanks for your interest in Syncfusion products.
You can achieve your requirement by using the MultiColumnTreeView's NodeEditorValidateString Event. For more information i have included a sample as follows.
[Sample]
http://www.syncfusion.com/uploads/redirect.aspx?&team=support&file=MCTVSamp-2005736597.zipPlease have alook on the above sample and let us know if you need further assistance.
Regards,
Iniyen M.A.