Abstract: A new method for fast preparation of β-receptor imaging agent:131I labelled m-io-dobenzyl guanidine （MIBG） was studied using Cu+ as catalyst. Labelling conditions have beenoptimised. A radiochemical yield more than 99%is obtained at l00℃ within 10 15min. Themethod is superior to earlier described methods, and it fulfills the requirments for kit labelling.