The invention provides a commodity transaction method and device based on a blockchain network, and a blockchain network node. According to the technical scheme provided by the invention, the merchant and the platform issue the coupons through fund mortgage, and the fund mortgage amounts of the respective issues of the coupons are subtracted when the merchant and the platform are subjected to share settlement, so that the preferential quota and share of the merchant and the platform can be clearly calculated under the condition of not changing agreements such as commodity contracts and share proportions, and the payment efficiency of the merchant and the platform is improved. Issuing and using of coupons are realized, namely commodity discounting is realized. Because the coupon is issued in a mortgage manner, the availability and authenticity of the coupon can be ensured according to the characteristics of the blockchain, and the mortgage is a preposed mortgage, so that the whole coupon use process, conditions, the income proportion, the preferential degree and the like are determined not to be tampered / modified, and dispute is avoided.