Abstract: In this paper,we studied on factors influencing transformation of hypocotyl protoplasts of mung bean (Phaseolus aureus).The experimental result showed th t lower pH,phosphate starvation and acetosyringone could activate the expression of the vir genes of Ti-plasmid in Agrobacterium tumefaciens and promote T-DNA transfer into mung bean cells to some extent through transient expression of GUS activity in mung bean cells. Higher pH and concentration of Ca²⁺ promoted transient expression of GUS gene in PEG-mediated DNA direct transfer.The activity of GUS gene increased with the increase of foreign plasmid DNA concentration in the range of 10-100μg. The transformed calli from mung bean hypocotyl protoplasts were selected on MSO medium containing 50 mg/L chloramphanicol after the protoplasts were cocultivated with A.tumefaciens strain C₅₈C₁ (pBZ6111 ),and confirmed by analysis of nopaline synthetase (NOS) activity.