It is studied that how to use profit sharing arrangement as an incentive mechanism to stimulate both parties of R&D outsourcing to reveal their private information and commit enough R&D resources or efforts. First, it is proved that the double-sided moral hazard in R&D outsourcing can not be totally prevented under traditional profit-sharing arrangement, namely, fixed, proportional or mixed profit-sharing arrangement. And a new mixed profit sharing arrangement is proposed, which is composed of a fixed transfer payment and allocation proportion, and proved to be able to prevent the double-sided moral hazard, and motivate both parties to reveal their private information and commit enough efforts.