An experiment was conducted to explore effects of combination of five different citrus rootstocks with five different scions on development of arbuscular mycorrhizas under pot culture and in the field in August 2003. The results show that colonization rate of arbuscular mycorrhizal ranged from 4.88% to 40.52%, and spore density from 347 spore/kg dry soils to 750 spore/kg dry soils. Development of Arbuscular mycorrhizas in different soil depths was investigated. The highest colonization rate and the highest spore density were found within the soil depth of 10~20cm. In Arbuscular mycorrhizal development, no significant difference was detected between Guoqing No.1/Trifoliate and Guoqing No.4/Trifoliate and between Caca Caca/Robertson No. 36/Trifoliate and Newhall/Robertson No. 36/Trifoliate. They were significantly lower than Washington Sanguine/Robertson No. 36/Trifoliate. Arbuscular mycorrhizal development with the combination of Red Tangerine + Trifoliate was the highest among the rootstocks and was significantly higher than the other rootstocks. A positive significant correlativity (p ≤ 0.05) existed between spore density and mycorrhizal colonization rate with citrus under pot culture. Moreover, a positive significant correlativity (P ≤ 0.01) was also found between spore density and mycorrhizal infection rate with all the experimented citrus in the field and under pot culture as well.