This paper studies the impact of demand information forecast on remanufacturing of the manufacturer．Two cases where there is a monopoly manufacturer and there are two competing manufacturers are researched respectively．Information sharing between the remanufacturer and the new product manufacturer is analyzed. The results show that demand information forecast is profitable for a monopoly manufacturer，the value of forecast information to the remanufacturer is related to his market sharing，investment coefficient and intensity of price competition and the remanufacturer has incentives to share his information with the new product manufacturer when the accuracy of demand information forecast is low．