The competition and cooperation of dual-channel supply chain tend to increase the demand uncertainty. By consideration of random demand fluctuations, the base stock model and stock-out model of manufacturer and retailer under independent and joint inventory decision modes of two-stage dualchannel supply chain were explored. By simulation and comparison of the two models, the effect of stock-out cost, demand fluctuations on base stock level, existing stock level as well as other indicators were analyzed, and  two modes of inventory costs were studied. It is proved that the joint inventory strategy is superior to independent joint inventory strategy due to reduction of respective cost as well as overall supply chain cost. Therefore, the joint stock inventory strategy of dualchannel supply chain can share stock and coordinate stock level, reduce risk of stock-out and finally significantly minimize supply chain cost.