Abstract: The effects of exogenous polyamine on the growth and development of arbuscular mycorrhizal fungi (AMF) and host plant in the symbiotic culture condition were investigated by micropropagating grape plantlets infected with AMF (Gigaspora margarita) and then treated with exogenous polyamine (PA) and polyamine biosynthesis inhibitor methylglyoxal bis (guanylhydrazone), MGBG. The effects of exogenous PA and MGBG on spore germination, hyphal growth of AMF and development of the host plant in symbiotic culture condition were analyzed. The results indicate that certain doses of exogenous PA have significant effect on symbiotic development, grape plantlets and AMF. AMF arbuscular abundance, hyphal length, spore number and infection rate increase after treatment with exogenous PA. Meanwhile, PA biosynthesis inhibitor (MGBG) has opposite effect which is suppressed by application of exogenous PA. This implies that PA also has significant stimulating effect on the growth and development of AMF in ex vitro conditions. Because exogenous PA activates AMF in the rhizosphere, potential AMF infection is enhanced. Thus, AMF symbiotic association with grape plantlets can establish at early weaning stage and develop with time.