Abstract: The Principle and construction of the Frceman ion source are brieflydescribed. The main experimental results are as follows: the average beamcurrent is 2--3 mA for ~(40)Ar~+ and 500--700 μA for ~(11)B~+. The maximum beamcurrent is 4.8 mA and 800 μA for ~(49)Ar~+ and ~(11)B~+ respectively. Divergent angleof transverse and longitudial is±2.1°. and 8.9°respectively. The gas consumptionis 1.5×10~5ml·Pa/min. The filament life is about 20 hours (~(11)B 500 μA). Theworking temperature ranges from 250 to 800℃.