Pumpkin hybrid（ Cucurbita maxima × C. Moschata），‘Qingnong No.2’and‘ Qingnong No.3’were taken as stock，and watermelon（Citrullus lanatus）‘Jingxin No.2’was taken as cion．Watermelon seedlings grafted with these 2 stocks were inoculated with Funneliformis mosseae，Glomus versiforme and Glomus intraradices，respectively．The grafted seedlings without inoculation with any of arbuscular mycorrhizal fungi（AMF）were taken as the control．The effect of different AMF on the growth and photosynthetic index of the grafted watermelon seedlings were evaluated．Results showed that AMF inoculation could enhance the growth and photosynthesis of the grafted watermelon seedlings．Among them，the effect of G. versiforme was maximum．The biomass of‘ Qingnong No.2’inoculated with G. versiforme were significantly higher than that of the other treatments．Its AMF infection rate，Pn，Gs，Ci，WUE and SPAD were higher than that of the other treatments by different degree．Therefore，it is considered that the combination of‘Qingnong No.2’inoculated with G. versiforme has better application prospect in the production of watermelon seedlings．